Although Jamie Moyer’s ERA and FIP are both well above his career average he is pitching just as well as he has over the past five years. His FIP is artificially inflated by an unsustainable high 15.3% HR/FB, while his ERA is up because of that HR/FB and a .312 BABIP, his highest since 1991. His K/BB and GB% are right in line with his recent performance, but he is doing it in a completely different way. Check how Baseball Info Solution has classified his pitches:

+-----------+-------+-------+-------+-------+
|           |  2006 |  2007 |  2008 |  2009 |
+-----------+-------+-------+-------+-------+
| Fastball  |  0.41 |  0.38 |  0.41 |  0.65 |
| Cutter    |  0.13 |  0.24 |  0.30 |  0.10 |
| Changeup  |  0.28 |  0.28 |  0.24 |  0.18 |
| Curveball |  0.10 |  0.08 |  0.06 |  0.07 |
| Slider    |  0.08 |  0.01 |  0.00 |  0.00 |
+-----------+-------+-------+-------+-------+

What? Why is this ‘crafty lefty’ with a very good changeup and serviceable cutter sudenly throwing almost 65% fastballs? He of the 81 mph fastball. Maybe BIS is just reclassifying some of his other pitches, calling some of his cutters and changes fastballs?

I went back and used the pitchf/x data and classified his pitches using my own k-means clustering algorithm (the pitchf/x classification system itself is not always entirely reliable, at times confusing cutters and sliders and before 2009 it did not differentiate between two- and four- seam fastballs

+--------------------+-------+-------+-------+
|  v RHB             |  2007 |  2008 |  2009 |
+--------------------+-------+-------+-------+
| Two-Seam Fastball  |  0.19 |  0.28 |  0.40 |
| Four-Seam Fastball |  0.21 |  0.17 |  0.24 |
| Cutter             |  0.24 |  0.21 |  0.07 |
| Changeup           |  0.28 |  0.28 |  0.21 |
| Curveball          |  0.08 |  0.06 |  0.08 |
+--------------------+-------+-------+-------+
|  v LHB             |  2007 |  2008 |  2009 |
+--------------------+-------+-------+-------+
| Two-Seam Fastball  |  0.33 |  0.26 |  0.42 |
| Four-Seam Fastball |  0.17 |  0.16 |  0.21 |
| Cutter             |  0.26 |  0.35 |  0.17 |
| Changeup           |  0.17 |  0.16 |  0.11 |
| Curveball          |  0.07 |  0.07 |  0.05 |
+--------------------+-------+-------+-------+

My numbers are reasonably in line with BIS’s so I am pretty comfortable with the differences not being a classification artifact. It looks to me like Moyer is throwing a ton more two-seam fastballs this year, coming at the expense of his cutter and changeup.

Ump Bump noted the trend back in May and suggested that maybe he lost the zone with his cutter, curve and changeup, and needed to go heavy with the fastball to keep his walks down. His in zone rate is way down and early in the season his walk numbers were up before they settled back to near his career average recently, so this might be the case. I am not entirely sure. Phillies’ fans what do you think? Do you notice the difference while watching the games?

Interestingly even with the change in pitch usage his K, BB and GB numbers are not far off his career numbers. One thing that has changed is his platoon split. Over his career he had a slight reverse platoon split (OPS: vRHB .741/vLHB .766), this year he has an extreme one (OPS: vRHB .920/vLHB .760). This is expected when you trade changeups (no platoon split) for two-seam fastballs (huge platoon split).