How much did Brian McCann actually improve in 2015?

Brian McCann had a bounce-back year at the plate in 2015. After struggling to produce in his debut season with the Yankees, McCann finally acquitted himself well with Yankee fans by raking to the tune of a .259/.331/.471 slash line and a 117 wRC+ in the first half. While McCann slumped in the second half (along with seemingly every other Yankee), he won the Silver Slugger award for catchers while posting a 105 wRC+ on the season, up 12 points from the year before.

How did McCann manage his offensive improvement? His batted ball profile doesn't lend much help. According to FanGraphs, McCann's soft-hit percentage in 2015 was exactly the same in 2014, at 15.2%, while his hard-hit percentage increased only slightly, from 31.0% to 31.5%. His line drive rate actually fell, from 22.2% to 16.7%. Likewise, it doesn't appear that he gained any significant boost from going to the opposite field to beat the shift. While he did manage to bunt for a hit three times, McCann started pulling the ball more, increasing his percentage of pulled balls in play from 44.1% in 2014 to 50.1% last year.

So McCann wasn't hitting the ball any harder, and he wasn't making an apparent effort to steal many hits by beating the shift. He certainly didn't seem to be getting lucky, with his BABIP mired at .235. No, his offensive comeback seems to have been driven by perhaps two simple factors; walks and power. 2014 was a miserable year in those departments for McCann, as he posted a career low in walk rate, and his second lowest ever isolated slugging figure.

2015 provided a correction, with his walk rate of 9.7% and his ISO of .204 both slightly surpassing his overall career averages. McCann's home run to fly ball ratio, as well as his overall fly ball rate, both increased in 2015. That, combined with his increase in pulled balls, seems to have driven his power surge, and subsequent career high in home runs (26). Successfully targeting the short right field porch at Yankee Stadium (McCann slugged .507 at home, compared to .372 on the road) may have been all McCann needed to boost his offensive numbers.

On the surface, McCann's 2015 was a step forward. However, his proficiency at the plate masked a decline in other facets of the game. In fact, his most alarming area of decline was almost invisible, as McCann's typically excellent framing numbers fell. The Yankees are well aware of the importance of framing. They were one of the first teams to put stock in its significance, and have long employed first-class framers, dating back to the days of Francisco Cervelli and Russell Martin. Much of the reason the team offered McCann such a lucrative contract two years ago was his proclivity for stealing strikes.

Last season may have been quite worrying to the Yankees with regard to McCann's performance. In McCann's debut season in New York, he was 11.4 runs better than the average catcher in terms of framing, according to StatCorner, while Baseball Prospectus rated him as 9.9 runs above average in 2014. Those numbers fell to 2.5 runs below average, per StatCorner, and 3.9 runs below average, per BP. So stark was his decline defensively that Baseball Prospectus actually valued his overall play in 2015 lower than his contributions in 2014 (2.4 WARP vs. 3.2 WARP), in spite of his strides on offense.

In light of this defensive regression, as well as the development of young catchers in the Yankees' system, it is tempting to think of a scenario in which New York hadn't splurged and signed McCann to an expensive deal. His five year, $85 million contract seemed almost inevitable at the time, given the dismal offense afforded by the Chris Stewart/Cervelli tandem in 2013. However, Cervelli has flourished as a starter with the Pittsburgh Pirates, and the departed John Ryan Murphy proved to be a serviceable backstop with the Yanks last year.

Further complicating matters is Gary Sanchez, whose development has given the Yankees another option behind the plate. At this point, it's difficult not to envision a world in which New York had simply stuck it out with Cervelli and Stewart (or Murphy) in 2014, before turning to the young catchers in 2015 and beyond. Such a chain of events certainly would have left the Yankees' payroll a little clearer, and when considering McCann's defensive decline, it's fair to ask if a combination of Sanchez and Murphy would soon equal, or surpass, McCann in terms of on-field value.

Of course, it is rather hypocritical for most of us to pine for a mulligan on McCann's contract, given the information we have now regarding players like Cervelli or Sanchez. I certainly was excited at the time that the Yankees exercised their financial wherewithal to fill what appeared as a glaring hole, and McCann has been a fine contributor for the past two years. His solid output has almost allowed me to forgive him for the all the times he anointed himself captain of the No-Fun Police.

Still, McCann is at something of a turning point with his time in New York. He's delivered quality production thus far, but warning signs regarding his defensive skills raise questions as to whether he will be able to sustain that production as he ages. How he answers these questions will go a long way towards determining whether the Yankees regard him as a worthwhile signing, or a regretful investment.