A.J. Burnett has largely been an underrated pitcher through his career. He was labeled as one of ‘those guys' who cannot pitch in New York. Despite amassing an fWAR over 40 for his career, he has never been selected for the All Star Game nor has he received any votes for the Cy Young award. Burnett can be characterized as a solid mid-rotation innings eater who provides league average performance over the course of many innings per year. Between 2001 and 2014, Burnett averaged 175 innings and approximately 27 or so starts per year.

From 1999 (his debut year) to 2005, Burnett started 131 games and had an earned run average 11 percent better than league average. Even in the early days he was a strikeout pitcher, K'ing approximately eight batters per nine innings. Burnett still strikes out that many batters but has evolved as a pitcher.

After the 2005 season, Burnett became a free agent and signed with the Blue Jays for three years, where again he was a better than league average pitcher, but nothing spectacular. In those three seasons he averaged 172 innings, a 3.82 FIP, and a 3.94 ERA.

The narrative of Burnett really takes hold when examining his short stint in the Bronx. Though it felt like forever to Yankee fans, A.J. was on the team for only three years of his five year contract before he was shipped to the Pirates following two seasons where his ERA- was 23/24 percent higher than league average. Burnett was never embraced by Yankee fans, and despite leading the majors in strikeouts in his last year in Toronto the only categories he led in pinstripes were walks, hit by pitch, and wild pitches. After three seasons, the Yankee brass had seen enough and sent him packing to PIttsburgh while also picking up a majority of his salary.

Burnett found decent success in Pittsburgh and did well with the teams' (then) innovative defensive alignment. Although he complained publically at times, he quickly turned into a fan favorite and led the Pirates to their first playoff series in two decades.

After the 2013 wild card game, there was a narrative surrounding Burnett's relationship with his teammates and with the PIttsburgh front office. It seemed plainly obvious he would not return to the team in 2014, and he signed a one year deal with Philadelphia. The friendly confines of Citizen's Bank Park did not do Burnett any favors nor did the losing ways of the Phillies. Burnett boomeranged back to the western side of the state this year.

So this is A.J. Burnett's swan song. He was transparent during the offseason stating that he had considered retirement but wanted to give the Pirates one last shot. Despite contemplating hanging up his cleats forever, so far in 2015 Burnett has posted the best year of his career. This is his age 38 season, and he currently (going into Wednesday night's game against the Tigers) has an earned run average 46 percent better than league average, at 2.01, and a FIP 29 percent better than league average, at 2.62.

Burnett has had a bit of luck on his side -- he has stranded runners at an 80 percent rate, which is ten percent higher than his career average. He is also giving up about half as many fly balls for home runs as he had previously. His strikeout rate has remained consistent to his career average, but his walk rate is down.

Interestingly enough, it seems that Burnett has changed his repertoire a bit in order to take better advantage of the shift he vehemently said he did not like. Per Brooks Baseball, Burnett has continued to decrease the use of his four seamer (likely as he comes to terms with a slight decrease in velocity that inevitably comes with age).

Burnett has increased the usage of his sinker and has relied less on his four-seam fastball, which seems to have boded well for him so far this season. His groundball rate is up four percent compared to his career average, but his strikeout rate is only a tick lower.

2015 can be a special year for Burnett. He's well on his way to his first all star nomination and will probably get some down ballot voting for Cy Young (rightly or wrongly). Burnett is likely quite pleased that he decided to pitch one more season, and Pirates fans are hoping he can help lead them to the pennant.

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Steven Martano is an Editor at Beyond the Box Score and a Contributing Prospect Writer for the Colorado Rockies at Purple Row. You can follow him on Twitter at @SMartano.