There's a big emphasis on "If".
I hesitated to say this for many, many years, but I think I'm confident in saying this now: Francisco Cervelli is a pretty good catcher. I say "pretty good" because I still don't think that's he at all worth a starting catching position, but he's certainly good enough to be a backup for just about any team. I, of course, was unwilling to admit this because he has never been healthy enough to remain playing long enough to see his true talent, combined with his steroid suspension last season. To say that his career has been mired with injuries is an understatement. The list includes a wrist fracture from a home plate collision, a fractured foot from a foul ball, a concussion from a home plate collision, a hand fracture from a foul tip, and a hamstring strain. And even though most of those are freak accidents, they still happened. That type of beating makes a player more injury-prone in the future, even though he's not actively putting himself in danger.
Even with all of that, I think we have a decent idea of where his talent level lies. This season thus far Cervelli has filled in another 107 plate attempts into his career, which gives us now a more considerable sample from which to draw from. Over 703 plate appearances in his career, Cervelli has hit 99 wRC+ and has accumulated 3.2 fWAR. For a backup catcher, that's not half-bad. The problem is, though, that this performance is spread out over a number of years. How can this be regressed to create a true talent level? That really depends on the projection system. ZiPS has confidence in this career performance--he's projected to hit 96 wRC+. Steamer, on the other hand, probably factors in luck and injury into its projections more heavily; it projects that Cervelli will only hit 82 wRC+ for the rest of the season. Even if it is the latter, he still has considerable value as a backup catcher.
The Yankees are good at developing catching, especially in regards to defensive catching. Defensively, Cervelli has been well above average, even if the sample may be limited. Over the span of his career, dWAR rates him as 1.5, and FanGraphs' Defensive Runs Saved has him at 9.3 runs. Either way, his defense is certainly suitable to fill in for the excellent defensive catcher in Brian McCann. In terms of pitch framing, Cervelli has also been more than just serviceable. According to Baseball Prospectus' catching data, Cervelli's receiving has produced 29.1 framing runs over his career; the rate of his production is 13.8 runs/7000 receptions. That's certainly not like the abilities of Brian McCann or Russell Martin, but it's much, much better than your average catcher. If we had a more accurate picture of him offensively, it'd be safe to say that he'd be an above-average backup.
This all doesn't mean that Cervelli has any trade value. At 28 years old and with his injury history, he offers virtually no upside and only two years of team control. That would be worth about a win or two, meaning the Yankees could maybe net a fringe-prospect at best. For their purposes, it'd be best to leave him in his current role.
I've always been down on Cervelli, and for good reason at the time. Up until last year, he had produced one excellent offensive month and had rarely been on the field consistently due to injuries. That one month in 2013 seemed even more like a mirage after his suspension; I wondered what his true talent level really was. I think it's safe to say that his offense is either average or slightly below average with defense and receiving that is above average. When most teams struggle to find a single decent catcher, the Yankees have a backup that doesn't look too shabby filling in on McCann's off days or during periods of injury. The Yankees may appear to have a logjam at the catching position, but logjams clear up pretty quickly. Cervelli should be a part of the Yankees' future, and rightfully so.