What seems to be sure about Burnett, though, is that a Pirates uniform brings out the best in him.
Burnett takes the hill as Pittsburgh seeks a rare victory at Busch Stadium in the series opener against the St. Louis Cardinals on Friday night.
After going 26-21 with a 3.41 ERA in two years with the Pirates, Burnett opted against retirement and instead moved his family closer to his Maryland home by signing with Philadelphia for 2014.
Burnett, who went back on his word after saying he'd re-sign with Pittsburgh or retire, discussed retirement again while going 8-18 with 4.59 ERA in Philadelphia. He then left more than $4 million on the table by declining a player option and agreeing to a one-year, $8.5 million deal to return to Pittsburgh in the offseason.
That appears to have been a wise decision. Burnett (0-1, 1.80 ERA) has allowed just five runs in four starts after giving up one in seven innings of the Pirates' 2-1 win over Arizona on Saturday.
It's the first time since Aug. 9-19, 2005, while with the Marlins that the right-hander has allowed fewer than two runs in three consecutive starts.
"It's different now than it was a couple of years ago with velocity and stuff," Burnett said. "I just pitch and not get stubborn thinking I can sneak some balls by the hitters. Sometimes I can set that up. Just pitch and use the movement to my advantage."
Burnett's best start with the Phillies came against the Cardinals on June 20, when he pitched his only complete game of the season in a 5-1 victory. That win came in St. Louis, where the Pirates (12-10) have dropped 14 of 17 including the 2013 postseason.
Pittsburgh lost the first two of its series with the Chicago Cubs before salvaging Wednesday's finale. Andrew McCutchen finished April hitting just .194, but he collected his 1,000th career hit and had a two-run triple in the 8-1 victory.
"It's nice to get out of here without getting swept," winning pitcher Gerrit Cole said. "We can relax a little more on the off day, clear our minds and get ready for St. Louis this weekend."
The Cardinals (15-6) improved to 8-2 at home by taking the final three of a four-game set with Philadelphia. Matt Adams hit a two-run homer and finished with three hits in Wednesday's 9-3 victory.
Adams is just 1 for 14 in his career off Burnett, but he enters this contest 8 for 13 over his last three as the Cardinals totaled 25 runs.
"When you get this offense really going, it's one of the best in the majors, and right now everybody it seems is producing," Adams said. "It seems like everything is starting to really come around, not just for me but for the offense itself."
Lance Lynn went 1-1 with a 1.56 ERA over his first three outings before giving up six runs and 10 hits in five innings of Sunday's 6-3 loss to Milwaukee. Lynn (1-2, 3.63) has made just one start at home, where he's 7-3 with a 1.83 ERA over his last 13 regular-season starts.
McCutchen is 6 for 38 (.158) with 14 strikeouts lifetime against Lynn, but the right-hander is just 1-3 with a 6.34 ERA in his last seven against the Pirates.