When he was first spoiled, Tezzeret, Agent of Bolas was one of the most talked about cards in Mirrordin Besieged. While he has performed well in some decks, including a top eight at PT Paris in the hands of Patrick Chapin and a SCG Qualifier win for Chase "The Tezzerexpert" Stefani (@DrunkestMan on twitter) at GP Denver, he has not seen nearly the amount of success the hype would have predicted.
There are several obstacles in Tezzeret's path if he is to become the cornerstone of a successful deck. He requires more help than other strategies (and is thus more inconsistent), he is more difficult to play correctly than many other strategies (which will further bring his success down), and he is more vulnerable to sideboard hate than many other decks.
Help wanted: To be useful, [card Tezzeret, Agent of Bolas]Tezzeret[/card] requires a fair number of artifacts in your deck. In order to consistently have an artifact in your top five cards, to avoid whiffing on his +1 ability, you need to have at least 60/5=12 artifacts in your deck. That is the bare minimum number required to consistently hit one artifact in your top five cards. As anyone that has played with Summoning Trap can tell you, however, the fact you are mathematically favored to see one specific card type in a given number of cards does not mean you always will - that's why we shuffle. The twelve artifact minimum also does not give you any extra card selection options - in a perfectly distributed deck you will see one artifact in the top five, but that means you are locked into taking that one artifact. [card Tezzeret, Agent of Bolas]Tezzeret[/card] is significantly stronger if you can see multiple artifacts and choose which one will suit you best at the moment. That means you have to play with an even larger number of artifacts in your deck, or you will not be using the +1 to its fullest potential. Not every card needs to be used to its fullest potential to be useful, as we can see in the use of Wild Nacatl in some RG decks or Mox Emerald in Vintage decks with no intention of casting Green spells, but a card's maximum potential is still worth knowing when using it as the cornerstone to a new deck.
The -1 ability does not require as many artifacts be in your deck as the +1, but it is still necessary to have some support to be used. Even if you only have one artifact, paying four mana for a 5/5 and making your opponent either attack with nothing or run the risk of seeing another 5/5 appear is a fairly good deal.
Tezzeret's ultimate is rarely relevant outside of situations involving Myr Battlesphere because most games are going to be finished by animating 5/5s before the -4 becomes threatening. If a quality token generator is printed in the next set I could see a deck being built to take advantage of his ultimate, but for the moment I will be focusing on the +1 and -1s.
The fact that Tezzeret requires a good bit of support is one of the largest obstacles to his success. Unlike [card Jace, the Mind Sculptor]Jace[/card], Ajani Vengeant, or other Planeswalkers that have been widely adopted and played, you can not just cut four cards from a given deck and jam in Tezzeret and expect it to perform well. [card Jace, the Mind Sculptor]Jace[/card] and Ajani Vengeant both have extremely powerful abilities that could be put to use regardless of the rest of the board state, but Tezzeret is useless without artifacts either in play or in your deck.
If you look at the non-Tezzeret decks in Standard today, there are very few artifacts seeing play. Tumble Magnet is starting to be more widely adopted, Boros and CawBlade both have [card Sword of Feast and Famine]Swords[/card] they can tutor for, and anyone playing Brian Kibler's Poison deck is going to have Contagion Clasp. Beyond that, almost nothing. This tells me something rather important: most artifacts aren't good enough. If more artifacts were good enough to see play on their own more decks would play them. The fact that artifacts haven't been more widely adopted means that they aren't good enough to see play on their own. That means that any Tezzeret deck that is trying to play with one or two dozen artifacts is jamming itself full of cards that other decks don't consider good enough. While they may be good enough to be threatening when [card Tezzeret, Agent of Bolas]Tezzeret[/card] hits the field, what happens when you don't draw Tezzeret or he is counterspelled? You suddenly have a deck filled with cards that most decks aren't playing because they don't have a strong enough impact on the field, which means your average topdeck without Tezzeret is going to be significantly weaker than your opponent's. If all goes well and you both resolve and protect Tezzeret, you may be fine, but the games that you don't draw Tezz or he is countered or immediately killed will leave you wishing for stronger, more relevant topdecks.
This is related to a question I ask anyone that has built a new deck they are sure is good: why hasn't this been seen before? If you are right and this really is as good as you think, why hasn't anybody else built it before now? You are hardly the only deckbuilder in the world and it seems a safe bet that given the number of players and number of people playing in tournaments all over the world, someone else has thought of something similar to this.
In the same way, when I see a deck full of cards that no one else is playing, such as the Tezzeret decks filled with Everflowing Chalices, Sphere of the Suns, Prismatic Lenses, etc., I ask: If these cards don't suck, why isn't anyone else playing any of them? They clearly are going to have more synergy in a Tezzeret deck than in other brews, but you can't build a deck living in Magical Christmas Land and assume you are always going to have the cards you are hoping for. Barring numerous tutors, your deck has to be able to function and do relevant things even if you don't draw one specific card, which means all the pieces have to be decent (or at least not vomit-inducing) topdecks on their own. Sure, Everflowing Chalice and Sphere of the Suns do relevant things even if you don't draw a [card Tezzeret, Agent of Bolas]Tezzeret[/card], but if what they did was really worth it on their own they would have been adopted by other decks. They haven't.
Difficulty: I believe that Tezzeret decks are also more difficult to play than many other strategies, a fact that hasn't seen much discussion. Boros requires a decent amount of math in regards to whether you play a Steppe Lynx on turn one or a Goblin Guide, as well as when to sacrifice the numerous [card Arid Mesa]fetchlands[/card], CawBlade demands a good idea of what matters most in any given matchup and how that can change depending on the board position, as sometimes you want to play a control deck and win a long game with [card Gideon Jura]Gideon[/card] and other times you can afford to race. [card Tezzeret, Agent of Bolas]Tezzeret[/card] brews, however, require both of these and more. Most lists that I have seen so far can function as either Control or Aggro depending on the situation, demanding its pilot know who is the beatdown on any given turn, much like CawBlade. It also requires its pilots to know what matters in a given matchup, and based on that what to do with their Tezz. At times they may want to attack opposing Planeswalkers before they can do more damage, and others they may want to attack the player directly and ignore the [card Jace, the Mind Sculptor]Jace[/card]/[card Koth of the Hammer]Koth[/card]/whatever.
Tezzeret also requires a number of skills that have never been seen before, most notably the decision of when to +1 and when to -1. Anyone that has played [card Wild Nacatl]Legacy[/card] [card Chain Lightning]Zoo[/card] can pick up [card Plated Geopede]Standard[/card] [card Lightning Bolt]Boros[/card] and have a fairly good idea of what they are doing with it. Someone that has played with [card Wing Shards]UW[/card] [card Decree of Justice]Control[/card] and/or [card Lord of Atlantis]Fish[/card] decks from formats past can decipher CawBlade without a terrible amount of difficulty, but there is nothing like Tezzeret from older formats that I know of. That means that players that are quite skilled in the fundamentals of Magic but don't have much time to thoroughly test new decks before playing with them on the day of a tournament are probably going to have more success with a deck other than Tezzeret because their previous experience will have more application. Someone brand new to the game with this standard format would have a bit more difficulty deciphering the correct lines of play than some other decks but would be fine with testing, but players that have been coasting on their experience with previous formats would be on new and unfamiliar ground.
This means that many people, in playtesting, are making mistakes when piloting the deck which would give them a false sense of the deck's power and capabilities. After deciding that the deck isn't very strong, there are fewer people willing to play Tezzeret-based brews in tournaments compared to other strategies. With a smaller percent of the metagame, there are naturally going to be fewer wins for Tezzeret, which results in fewer people playtesting the deck... you can see where this is going.
Hate: Another obstacle in the way of Tezzeret's success is that it is more susceptible to sideboard hate than some other decks in the format. The fact that Tezzeret requires a large number of artifacts to be successful is a large chink in its armor as there are a plethora of artifact destruction spells available to virtually every deck, and many decks are already sideboarding those spells to deal with opposing [card Sword of Body and Mind]Swords[/card] due to their stranglehold on the current format. Building a new deck is an admirable undertaking, but if you build a brew that is susceptible to existing hate that people are playing without taking your deck into consideration you are probably not going to accomplish much.
An example of this that came to mind is from Extended from several seasons ago, one of the last seasons before Extended was shortened. A popular deck at the time was Scepter-Chant, a UW or UW/r Control deck that played Isochron Scepter and Orim's Chant to lock an opponent out of the game. It was a tier one deck and one of the premier Control strategies. Then Time Spiral was released, and with it Ancient Grudge. People started playing with the Grudge to deal with Scepter-Chant, and overnight Affinity dropped off. Affinity wasn't a huge chunk of the metagame at the time and people weren't specifically gunning for it - it was just vulnerable to hate cards that people were already playing to deal with a more popular and dominant deck. In the same way, [card Tezzeret, Agent of Bolas]Tezzeret[/card] decks are vulnerable to Divine Offering, Manic Vandal, Nature's Claim, Acidic Slime and other answers that people are already playing to handle Sword of Feast and Famine and Sword of Body and Mind.
Possible Fixes: One option that could be explored is adding more powerful cards to the deck that don't operate on the same principals as the rest of the deck. Tezzeret, Agent of Bolas-centric decks are built on synergy. Tezzeret turns otherwise unplayable artifacts into 5/5s. The mana artifacts are there to accelerate out a turn three Planeswalker, giving the deck a strong enough early game to make up for the fact that those same artifacts are worse in the late game. The entire deck is built around synergy and letting the pieces form a larger whole than the sum of their parts. This opens the door to being overly reliant on one card (Tezzeret) and crumbling if it isn't drawn/doesn't resolve, while also making the deck more vulnerable to hate cards. Instead of going all-in on synergy, why not play a large threat or two that is capable of dealing some serious damage on its own? One option that is worth considering is adding a few titans. A Grave Titan or Inferno Titan would be a significant threat on its own and would be able to help a Tezzeret player out even if their Tezzerets were countered or weren't drawn, or if the opponent sideboarded in significant amounts of hate. Chase Stefani won a Qualifier with a Tezzeret build that was two cards different from Patrick Chapin's list at PT Paris, but this is his latest brew:
[deckbox did="a55" size="small" width="567"]
The changes from the PT Paris list are swapping out the Treasure Mage and tutorable Wurmcoil Engine and Mindslaver for a trio of Inferno Titans as well as changing from two Stoic Rebuttals to a fourth Sphere of the Suns and Tumble Magnet. The Inferno Titans provide another way to win that is not as dependent on resolving Tezzeret, Agent of Bolas as the rest of the deck, while the additional Sphere of the Suns provides additional mana fixing for a manabase that is being stretched further than before, as well as an additional accelerator for the higher mana curve. The Tumble Magnet is additional protection against the many [card Sword of Feast and Famine]Swords[/card] floating around today's metagame.
With no counterspells the Valakut matchup is going to be weaker than it was previously. The Tumble Magnets are good at buying time against Overgrown Battlements or, later, Primeval Titans and with six early removal spells there is a good chance of taking out a Lotus Cobra before serious damage is done, but I don't think this deck can expect to race a Primeval Titan and its accompanying [card Valakut, the Molten Pinnacle]Valakuts[/card]. When Valakut gets a hand full of Explores and Harrows it seems like a disaster waiting to happen.
With Valakut on the decline, however, that might be OK. It is certainly solvable after sideboarding with Spell Pierce, Mana Leak, Spreading Seas[card] or other options, and almost every deck has at least one weak matchup. With four board sweepers and four [card]Tumble Magnets, this deck is clearly aiming more at aggressive decks and public enemy number one, CawBlade.
Another option for a Tezzeret deck is to play with White instead of Red. This would allow the deck to play Gideon Jura, who can take the place of the Inferno Titans in providing a way to win that is not reliant on Tezzeret, while also providing significant defense to either protect your other Planeswalkers or buy you time to dig for a Tezzeret. Playing with White would unfortunately push Tezz into playing with Day of Judgment instead of Pyroclasm and Slagstorm, which is probably a downgrade. Almost every creature seeing play today dies to Slagstorm, and the ones that don't are pretty much all Titans. The Titans are fairly rare, and can be handled by Tumble Magnets long enough to either race or permanently handle them with [card Gideon Jura]Gideon[/card]. Against Kuldotha Red and Boros, however, the lowered mana cost on Pyroclasm and Slagstorm makes them a significant upgrade compared to Day of Judgment. Playing with White instead of Red would also allow the deck to play with Celestial Colonnade in addition to Creeping Tar Pit, if desired, which seems stronger than Lavaclaw Reaches as manlands numbers five through eight.
Good luck brewing!