Statistically Comparing Chase Headley (2017) to J.A. Happ (2019):

In 2017, Chase Headley hit to a slashline of .273/.352/.406 (.758 OPS) with a perfectly league average OPS+ of 100. He also played in 147 games season between both first and third base. This was his best offensive season that Headley had (he put up +2.6 oWAR) since the 2013 season (where he had a +3.0 oWAR), but his worst defensive season (-0.9 dWAR) since 2009 (-1.7 dWAR).

This defensive dip was probably because he was asked to play a platoon of first and third base after Todd Frazier was acquired before the Trade Deadline, but overall Headley produced +1.9 bWAR in the 2017 season. This was also one year removed from a +2.6 bWAR season in 2016, and back-to-back +3.4 bWAR seasons in 2013 and 2014. Headley was by all means a solid player during his career and the Padres were looking to capitalize on grabbing the final excellence of his career.

Unfortunately for the Padres, Headley only managed to play 60 games for them in 2018, where he hit an abysmal .115/.233/.135 (.368 OPS) with an OPS+ of 7. It didn’t work out for them and Headley was DFA’ed in May of that season.

In 2019, J.A. Happ pitched to a record of 12-8 over 161.1 innings with an ERA of 4.91, a FIP of 5.22, and a WHIP of 1.295. All this combined to a less than league average ERA+ of 90. Happ was however still worth +1.2 bWAR in 2019, which is only slightly below his career average bWAR/season of +1.7.

This dip also came after Happ had put up a fantastic 2018 season totaling +3.3 bWAR for the Toronto Blue Jays and Yankees, and the three following seasons all had bWAR’s above 2.5: +2.6 bWAR in 2015, +4.5 bWAR in 2016, and +3.3 bWAR in 2017. Like Headley, a team that would acquire Happ would be looking to capitalize on trying to get the last excellence of his career.

Obviously, we have no idea how well (or poorly) Happ will perform during the 2020 season, but Baseball Reference has a wonderful projection tool that has J.A. Happ pitching to a 12-8 record with a 4.50 ERA and a WHIP of 1.291 in 158 innings, with a reliability factor for this projection at 77%. This shows that these projections expect Happ to stay consistent, as these numbers match up very well with his statistics from 2019.