Bill Belichick has always liked having 2 good TEs on the roster because that personnel grouping gives the Patriots more versatility in their offensive looks, especially out of base/12 (1 RB, 2 TE) personnel. When the Patriots won 3 titles in 4 seasons from 2001-2004, the main TEs were Christian Fauria and Daniel Graham. They drafted Ben Watson in the first round in 2004, who was a solid player but never really produced to his draft status even though he had a strong first half in 2007. It wasn't until 2010 that the Patriots had two players at the position that could dictate matchups when they drafted both Rob Gronkowski and Aaron Hernandez. Obviously Hernandez isn't ever suiting up for an NFL team again, but the Patriots did make a significant TE acquisition in the offseason with Martellus Bennett.
The Patriots went 2 TEs 54.7% of the time back in 2011 with Gronk and Hernandez combining for well over 2000 yards and 24 TDs. The Patriots have not been able to capture the same 2 TE dynamic ever since due to injuries for Gronk and off-field problems for Hernandez that will likely be rehashed in the comment section below. We all know what Gronk can do on the football field and having a 2nd reliable TE does not affect his production in the least. When healthy, you can expect 70 catches, 1100 yards, and 10 TDs as his baseline. Martellus Bennett is more in the mold of Gronk than Hernandez at TE, which could give the Patriots even more versatility in their play-calling. The Patriots can utilize Bennett in a similar capacity they used Hernandez on the football field in addition to being a strong inline blocker either next to or on the opposite side of Gronk.
It's unclear if there will be a shift towards more 12 personnel groupings in 2016, that's a circumstance that's dictated more by who's available. Bennett may not even figure out the playbook easily, although he can ask Gronk for help on that front. At full strength, the best five skill players for the Patriots (Gronk, Edelman, Hogan/Amendola, Bennett, Lewis/Blount) best fit 12 personnel due to their ability to dictate matchups in both the run and pass game. Teams don't have the physical talent to cover those five in space and if teams try to match speed and quickness then they can be overpowered in the run game when the Patriots condense the formation to a more traditional 2 TE look with both TEs on the line. That personnel grouping has the most potential in the red zone, with two targets taller than 6'6" and the other three with ridiculous short-area quickness.
Even with the amount of work put into offseason mini-camps as well as training camp practices, the fans won't be able to see the Gronk and Bennett dynamic until Week 1 of the regular season in Glendale, AZ. The tandem of Gronk and Bennett will be overhyped, with this article taking a big part of the blame for that, to start the season and most likely Bennett will start off slowly adapting to a new environment. Gelling into the offense is something that doesn't happen overnight and it's a reminder to stay patient. However, by the end of the season I do expect the Patriots TE dynamic to be just as good, if not better, than the duo they had in 2011.