Joel Hanrahan and peripheral stats
When the Pirates acquired Joel Hanrahan from the Nationals, I immediately noticed the huge discrepancy between his peripherals and his unsightly 7.71 ERA. Hanrahan struck out 35 batters, walked 14, and allowed three home runs in his 32.2 inning with Washington this year. That comes out to a FIP of 3.60, more than four runs lower than his actual ERA. I immediately liked the acquisition, as it seemed obvious that Hanrahan’s absurd .451 opponent’s BABIP was dramatically damaging his numbers. Superficial improvement seemed imminent, regardless of any authentic progress being present.
Fast forward to today, August 28. Hanrahan has thrown 19.2 innings for the Pirates, with an impressive 25 strikeouts, a less impressive 11 walks, and zero home runs allowed. His FIP with Pittsburgh is 2.37, and his ERA is a much improved 2.75. The walks are concerning, as the one knock on Hanrahan has always been poor control. Even with the excellent strikeout rates, he will need to focus on limiting his walks in order to be successful.
Another concern I have with Hanrahan is that, despite his high strikeout numbers, he remains very hittable when the ball is put in play. His Pittsburgh BABIP is less outrageous than it was in DC, but it remains a very high .396. This is probably due to his high opponent line drive rates, which jumped from an already elevated 24.1% with the Nats to 28.8% with the Pirates. When opposing hitters make contact, they are hitting Hanrahan hard. Combine that with his high walk rates, and you have far too many base runners when Hanrahan is on the mound.
Due to the unusual combination of low contact percentages and high line drive rates, Hanrahan’s tRA is probably the best indicator of his performance. tRA places a run and out value on every event (K, BB, HBP, line drive, ground ball, outfield fly ball, infield fly ball and home run) and totals everything up to provide expected runs allowed per nine innings. (Keep in mind that this number will be higher than ERA, as it uses total runs as opposed to earned runs. I believe multiplying tRA by 0.92 will adjust it to the ERA scale.) Using tRA allows us to get a better grasp on the value of a pitcher who has a high K%, BB%, and LD%.
The 2009 league average tRA has been 4.39 for relievers. Hanrahan’s tRA with the Nationals was 4.36. His tRA with the Pirates has been 3.15. Hanrahan was about average in Washington, despite his high ERA. He has been very good with Pittsburgh.
P.S. Sean Burnett’s tRA with Pittsburgh was 5.22. With the Nats, it has been 4.39.