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.
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