J.A. Happ’s career can be divided into three phases.
First, there was J.A. Happ, the prospect. Coming up through the Philadelphia system, Happ compiled a 2.30 ERA in 2005, a 2.69 ERA in 2006, a 5.02 ERA in 2007 for Ottawa (hey, it was a bad year), and a 3.60 ERA with 151 strikeouts in 135 innings in class-AAA in the first part of 2008. This earned him a callup to the Phillies, where he made a few spot starts and relief appearances. In 2009, he moved into the starting rotation in late May (this is back when the Phillies were still good) and wound up with a 12-4 record and two shutouts (tying the league lead). He was the runner-up for Rookie of the Year. Then, he got hurt, and was traded to Houston as part of a package for Roy Oswalt (the package also included Anthony Gose, coincidentally).
I don’t know whether it was the injury, or whether he just didn’t like Houston, but this was the start of Phase 2 of Happ’s career: J.A. Happ, the mediocre starter. Starting in 2011, Happ pitched regularly in the rotation and compiled ERAs of between 4.22 and 5.35, many of which were with the Blue Jays. In 2015, he started off doing more of the same, going 4-6 with a 4.64 ERA. He was then traded to Pittsburgh, where suddenly he was transformed.
Phase 3 of Happ’s career is J.A. Happ, the unexpected ace. In a Pirate uniform, Happ had an ERA of 1.85 in 11 starts, and went 7-2. He had only one bad outing – his first. After that, it was one good start after another.
The Jays are clearly hoping that Phase 3 will continue. It doesn’t seem likely, given that Happ has spent most of his career in Phase 2. But then you could never have predicted that Phase 3 would happen at all, so you never know. One concern: even in Phase 3, Happ didn’t go deep into games – he had one seven-inning outing, but all of his other starts were six innings or less. He’s going to need help from his bullpen if he is to succeed in Toronto.