Mesoraco had been a highly rated prospect, although he struggled in his first full season in 2013. He broke out in 2014, hitting .273/.359/.534 with 25 home runs, leading all catchers in home runs and slugging percentage. He wasn't just taking advantage of Great American Ballpark either, as 11 of his 25 home runs came on the road and he posted nearly identical OPS splits (.896 at home, .890 on the road). Using the ballpark-adjusted wRC+ (weighted runs created), Mesoraco ranked as the best-hitting catcher in the majors with a 147 wRC+, just ahead of Buster Posey and Russell Martin.
Is there anything in the numbers that says fluke season? Not that I can see. He hit right-handers (a big improvement from 2013) and left-handers nearly equally as well. Among players with at least 250 plate appearances, he did rank seventh in the majors in his percentage of home runs per fly ball. Is the power legit or did he luck into a few extra home runs? Mesoraco's average home run distance of 390 feet isn't anything special but according to the ESPN Home Run Tracker, his total of "just enough" home runs was five, which is way below the league leaders in that category.
Mesoraco didn't have many "just enoughs" because nearly every home run he hit was pulled -- he hit one homer to center field; the other 24 went to left or left-center, including 14 to the "far left," making him one of the most extreme dead pull hitters in the majors. Mesoraco wasn't shifted much in 2014, but I suspect that will change in 2015, although that shouldn't affect his power output.
That doesn't answer the question of whether it was a fluke season. I thought it would be instructive to see how many catchers even had a year like Mesoraco, so I found all catchers with at least 400 plate appearances since 1969 who posted a wRC+ of 140 or higher (via FanGraphs). We get a list of 51 seasons from 29 catchers. Ten of those 29 posted more than one 140 wRC+ season, led by Mike Piazza's seven. Of the other 19 catchers, I'd say five could be classified as flukes:
Dick Dietz, 1970 Giants: .300/.426/.515, 152 RC+. It wasn't a completely fluke season, as Dietz posted a 132 wRC+ in 1971, although his average fell from .300 to .252. Dietz's story gets even more interesting. Even though he was one of the best-hitting catchers in the majors and even though the Giants had won the NL West in 1971, the Giants placed him on waivers three days before the start of the 1972 season. Why? Dietz was the Giants' player rep and the players had gone on strike during spring training, delaying the start of the season. The Dodgers picked up Dietz, he broke his wrist and then played well in a part-time role with the Braves in 1973 (.474 OBP in 191 PAs), but the Braves cut him the next spring and nobody picked him up. Bruce Markusen has the story of the possible blackballing of Dietz here.
Rick Wilkins, 1993 Cubs: .303/.376/.561, 144 wRC+. A stone-cold fluke. Hit 30 home runs but never posted a 100 wRC+ the rest of his career.
Paul Lo Duca, 2001 Dodgers: .320/.374/.543, 140 wRC+. A lot of silly things happened around this time. Lo Duca's season was one of those as he hit 25 home runs, 12 more than he hit in any other season. Later cited in the Mitchell report as a user of steroids and human growth hormone.
Alex Avila, 2011 Tigers: .295/.389/.506, 140 wRC+. Driven by a .366 BABIP, he hasn't come close to hitting like this again as his BABIP normalized and his strikeout rates increased.
Carlos Ruiz, 2012 Phillies: .325/.394/.540, 152 wRC+. The second-best mark of his career is a 127 wRC+ the season before, but he added more power in 2012 to his on-base skills. After the season, he tested positive for amphetamines and was suspended 25 games for 2013.
I don't believe Mesoraco is another Wilkins or Avila, but it's also likely he won't produce the same triple-slash line again (in part, because he may get an extra 100 PAs or so, which could create some fatigue). I'm guessing he'll have to make some adjustments as pitchers change their patterns against him. He hit .313/.460/.687 on inside pitches as opposed to .191/.271/.312 on pitches on the outer third or off the plate.
As for the contract, it should be a good deal for the Reds. Mesoraco is entering his age-27 season so the Reds will get him through his prime years and if he hits anything like he did in 2014, he's going to be a bargain the last couple of seasons of the deal.
Reds fans may have wanted to see a deal for Johnny Cueto, but they should happy about this one.