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Est. Wins using Fip for and Against

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After reading Matthan's fanpost this morning, I wanted to see what my offseason analysis called Est. Wins looked like through this point in the season.  This was a first look at how many wins a pitcher should have had.  It was rough and rudimentary.  Here is what it looks like updated through 75 games:

Pitcher  R   IP   R/IP  Starts  PROBw   Est. Wins 
Shields    2.88    6.77    0.42 16        0.522              8.35
Garza    2.67    6.49    0.41 15        0.556              8.33
Niemann    2.71    5.17    0.53 14        0.477              6.68
Sonnanstine    4.07    5.44    0.75 15        0.354              5.31
Kazmir    4.56    5.07    0.90 9        0.314              2.83
Price    3.67    5.06    0.73 6        0.429              2.57
Team    3.31    5.81    0.57 75        0.454            34.07


After conversing back and forth with Matthan I wanted to see this in FIP format, first the data, then the explanation:

Pitcher FIP PROBw  Starts   Est. Wins 
Shields           3.79 64.3%               16         10.29
Garza           4.67 50.8%               15           7.61
Sonnanstine           5.63 46.3%               15           6.95
Niemann           4.81 44.6%               14           6.24
Kazmir           6.11 41.9%                 9           3.77
Price           5.82 34.2%                 6           2.05
Team           4.96 49.2%               75         36.92

First off, check out the workbook on google docs or download the file FIP win% 75 games.  I ask to do this so the process doesn't come across as complete gibberish.  Using Baseball-reference's gamelogs I was able to come up with a game by game FIP for opposition pitchers (FIPa).  It stands to reason that if our starter has a lower FIP (FIPrays) he should be credited with a win.  From here I was able to create a matrix comparing each individual FIPa to the entire population of Rays starters FIPs.  Using conditional formatting (green is >1, or that cell represents an event where the FIPrays > FIPa) I came up with a total number of events where our performance should be better than theirs.  This yielded a probability of a win for each FIP that we have had this year (% of games on Matrix tab).

From here I moved on to the "Data" tab of the workbook.  By comparing each actual game FIP to the probability of winning at that FIP (PROBw) I was able to get an idea of estimated wins.  This was then totaled and put into the summary that you see before the jump.  The team FIP is a weighted average based on Individual FIPs and games started.  The PROBw is the likelihood of a starter winning any given starter, based on Est. Wins / Starts. 

I used 3.15 as my FIP constant term.  Our starter FIPs are based on actual Innings Pitched, while FIPa is based on all opposition pitchers, assuming 9 innings/game.  Overall, I really like this, and in the future will make the matrix a little bit different so it is easier to update.  It took a long time to do the matrix manually, so if anyone is any good at programming/macros it could be a lot easier in the future.  Your thoughts?