Out of Whack ERAs
Since we are around the halfway point of the season, I have decided to look into which pitchers have ERA’s that differ the most considering their FIPs, xFIPS and BABIP. I used all 3 values helps to find out truly lucky or unlucky pitchers have been this season and the reasons why (i.e. high home run rates or low BABIP).
To start with I took all the pitchers that have pitched over 20 innings so far this season. From this group, I averaged 3 numbers. ERA-FIPs (E-F) is already provided here at Fangraphs. Also, I easily calculated the ERA-xFIPS for the second value.
For the third value, I did a calculation of expect ERA using the batter’s BABIP from this quick calculation of Tom Tango.
The BAPIP ERA formula ends up working out to be:
(((0.300-BABIP)*(Total Batters Faced)) * 0.75) + Earned Runs)/(IP/9)
Explanation of constants (these 2 values can be adjusted if a someone wants to calculate the values themselves):
0.300 = league average BABIP
0.75 = Run value for an extra hit
With all three values calculated, I averaged them into a value determining how much a pitcher’s ERA differentiates from their expected ERA.
I have collected at the pitchers and posted them in this following Google Spreadsheet.
Note: For ease, I will use pERA as the projected ERA considering the pitcher’s FIPs, xFIPs and BABIP
Here are some highlights:
Chad Qualls – (ERA = 8.60, pERA = 4.03) – Chad is by far the unluckiest pitcher so far this season. He has not be exactly lights out, but no pitcher can be good with a BAPIP of 0.468.
Jose Valverde – (ERA = 0.92, pERA = 3.13) – No real surprise that a pitcher can’t mainly a sub 1 ERA. He got to the low ERA with a 0.169 BABIP and giving up only 1 home run so far this season. Jose is actually is striking out less and walking more batters than Chad Qualls.
Tim Hudson – (ERA = 2.30, pERA = 4.04) – Tim’s ERA has been helped in that he has 0.232 BABIP. He has needed a low BABIP since he has not been striking many people at all with a K/9 of 4.5 to go along with a BB/9 of 3.2
Francisco Liriano – (ERA = 3.86, pERA = 2.69) – Most people would complain too much about a starter with a 3.86 ERA, Mr Liriano looks like he should be doing better. He has a great K/9 of 9.8 and BB/9 of 2.5 while allowing only 2 home runs so far this season.
Jeff, one of the authors of the fantasy baseball guide,The Process, writes for RotoGraphs, The Hardball Times, Rotowire, Baseball America, and BaseballHQ. He has been nominated for two SABR Analytics Research Award for Contemporary Analysis and won it in 2013 in tandem with Bill Petti. He has won four FSWA Awards including on for his Mining the News series. He's won Tout Wars three times, LABR twice, and got his first NFBC Main Event win in 2021. Follow him on Twitter @jeffwzimmerman.
as far as Hudson goes… is there a formula that uses GB%/LD%/FB% to generate xBABIP first and generates an expected ERA from that? Hudson gives up the lowest LD% by a wide margin (10.6%; next lowest is 13.1%; MLB average is probably 18-19 or so) and the highest GB% by another wide margin (67.4%, Masterson is next with 63.2%, then it drops to 58.8%; league average is probably 45% or so) and the second-lowest FB% (after Masterson).
Also, wow is Masterson getting hosed by his defense, I guess.
I believe tERA does (3.66 for Hudson) but I’m not sure exactly how it is calculated.
Masterson’s D is letting him down, but he’s also benefited from an unusually low LD rate, so given all things, I wouldn’t consider him to be tremendously “unlucky”.