Addition by addition and subtraction.
It's always a win-win situation when a team is able to poach a talented player away from a division rival.
After losing tight end Anthony Fasano to the Kansas City Chiefs, the Dolphins were staring at the prospect of either Charles Clay or Michael Egnew as their leading tight end for 2013. Instead, they added a talented but limited tight end who should give them the answers they're looking for.
Jets quarterback Mark Sanchez built a comfort with Keller over the years, but the rapport was almost instantaneous. Sanchez targeted Keller 82 times as a rookie, and the two connected for 45 catches (54.9 percent), 522 yards and two touchdowns in that 2009 season.
Compare those numbers to what Tannehill had with Fasano—69 targets, 41 receptions (59.4 percent), 332 yards and five touchdowns—and it's easy to see why the Dolphins felt Keller could replace Fasano, with Keller more athletic overall but less of a red-zone threat.
That being said, he isn't completely incapable in that area, as the Dolphins found out in Week 17 of the 2011 season.
On 3rd-and-goal from the 1-yard line, the Jets ran a play-action bootleg with Sanchez rolling to his right. The Dolphins were prepared to stop the run, but weren't completely unprepared for the possibility of a pass, either.
However, once Sanchez started to move toward the line of scrimmage, the defense lost its assignments, allowing Keller to get open behind the defense for the easy score.
That play look familiar to you at all? That's because the Dolphins ran almost the exact same thing against the Jaguars, with Jorvorskie Lane on the receiving end of the score.
It wasn't out of the I formation, but there was still a play-action fake involved (Reggie Bush motioning from right to left, as indicated by the blue arrow).
Tannehill, rolling to his right, read the defense and waited for his man to come open.
Lane caught the pass for the easy touchdown.
The fact that Lane, a 277-pound fullback, was the one catching that pass tells you all you need to know about the Dolphins' passing game in 2012.
It should also tell you all you need to know about why they targeted a player with Keller's resume.
Erik Frenz is the AFC East lead blogger for Bleacher Report. Be sure to follow Erik on Twitter and "like" the AFC East blog on Facebook to keep up with all the updates. Unless otherwise specified, all quotes are obtained firsthand or via team press releases.