EWSL 2012 Age and Rookie Baselines

It’s that time of year again – it gets later every year – for my division previews powered by Established Win Shares Levels (originally explained here): before we get to rolling out the 2012 EWSLs, I have to update the age adjustments and rookie values I use each year. These are based on the data I have gathered over the past eight seasons, and so with each passing year, one would hope they become progressively more stable and useful in evaluating the established talent base on hand for each team entering each season. As a reminder: EWSL is not a prediction system. It’s a way of assessing the resources on hand.
To my mind, the age data is actually some of the most interesting stuff from this whole project, arguably more useful than the annual team previews, because it’s a mostly objective (albeit unscientific) dataset that gives us a different look at the aging curve from the perspective of the guys who look like they have roster spots in March and April of each year.
I’ll skip some more of the usual preliminaries (see this post from 2010 explaining more) and get right to the charts:
Non-Pitchers 2011 and 2004-2011:

2011 NP 04-11
Age # WS EWSL % # WS EWSL %
21- 3 55 48 1.146 9 127 107 1.187
22 2 26 33 0.793 30 462 260 1.779
23 4 53 33 1.603 71 865 704 1.229
24 22 286 205 1.393 137 1788 1368 1.307
25 22 270 238 1.137 195 2292 1906 1.203
26 28 304 246 1.235 241 2718 2491 1.091
27 43 569 495 1.149 277 3174 2997 1.059
28 41 457 481 0.950 280 3255 3227 1.009
29 29 350 350 1.000 253 3010 3103 0.970
30 31 358 361 0.992 261 2939 3239 0.907
31 32 240 378 0.636 241 2436 2969 0.821
32 23 264 308 0.857 219 2167 2695 0.804
33 24 173 247 0.701 189 1901 2230 0.853
34 17 174 183 0.953 163 1672 1923 0.869
35 26 231 314 0.735 148 1256 1702 0.738
36 6 42 63 0.665 96 904 1217 0.743
37 11 102 175 0.583 75 622 989 0.629
38 1 5 11 0.476 50 399 587 0.680
39 7 49 74 0.661 39 358 481 0.744
40+ 5 21 40 0.525 43 282 523 0.540
377 4029 4282 0.941 3017 32627 34716 0.940

The younger age cohorts, as usual, were volatile due to their small sample size. Among the 20somethings, the 28 year olds got hit the hardest (led by Joe Mauer, David Wright, Shin-Soo Choo, Kendry Morales, Casey McGeehee, Stephen Drew and Franklin Gutierrez), while the 26 year olds did the best (led by Matt Kemp, Matt Joyce, Emilio Bonifacio, and Melky Cabrera); the 31 year olds (led by Adam Dunn, Adam LaRoche, Felipe Lopez, Juan Uribe and Ryan Spilborghs) and 33 year olds (led by Chone Figgins, Marlon Byrd, Rafael Furcal, and Luke Scott) also took it on the chin, and as has been the pattern since the end of the steroid/Barry Bonds age, the over-35 crowd did more poorly than the overall results since 2004.
Pitchers 2011 and 2004-2011:

2011 P 2011 Total
Age # WS EWSL % # WS EWSL %
21- 1 12 8 1.500 11 85 64 1.328
22 3 29 18 1.656 36 294 224 1.312
23 14 121 90 1.339 76 583 496 1.175
24 16 94 93 1.016 120 850 754 1.127
25 21 144 136 1.062 184 1306 1172 1.114
26 27 238 169 1.408 231 1624 1459 1.113
27 39 244 319 0.765 231 1492 1692 0.882
28 30 218 232 0.938 219 1497 1595 0.939
29 25 152 157 0.967 202 1299 1498 0.867
30 18 137 153 0.897 188 1158 1373 0.843
31 13 74 99 0.744 173 1037 1326 0.782
32 21 123 154 0.801 141 865 1099 0.787
33 17 69 106 0.654 116 628 892 0.704
34 16 100 137 0.730 99 562 708 0.794
35 9 80 70 1.137 70 387 477 0.812
36 10 86 85 1.016 61 363 400 0.908
37 4 11 19 0.595 46 274 344 0.797
38 2 2 22 0.093 44 284 361 0.788
39 1 2 6 0.364 30 210 247 0.851
40+ 5 31 40 0.769 73 494 693 0.713
284 1917 2058 0.931 2343 15242 16821 0.906

Besides the youngest arms, the 26 year olds (led by Ian Kennedy, Justin Masterson, Eric O’Flaherty, Fernando Salas and David Robertson) and 35 year olds (led by Kyle Farnsworth, Scott Downs, Freddy Garcia, and Joel Peralta) had the best 2011 showings; the 24 year olds (led by Tommy Hanson, Jaime Garcia, Tommy Hunter and Brian Matusz) and 27 year olds (led by Josh Johnson, Ubaldo Jimenez, Andrew Bailey, Joakim Soria, Jonathan Broxton, and Kevin Slowey) the worst aside from an overall decay above age 30.
We wrap up with the rookie adjustments:
Rookies

Type of Player # in 2011 WS in 2011 # 2004-11 WS 2004-11 Rate
Everyday Players 9 82 75 793 10.57
Bench Players (Under 30) 4 16 70 269 3.84
Bench Players (Age 30+) 0 0 4 3 0.75
Rotation Starters 2 8 34 146 4.29
Relief Pitchers 6 11 24 107 4.46
TOTAL 207 1318 6.37