Going into 2010, Ubaldo Jimenez was known as a potential big-time ace. He had just finished the 2009 season with a 3.47 ERA and had a 3.63 xFIP to make it clear that this improvement was, in fact, real.
In 2009, Jimenez had two fastballs that both averaged over 96 MPH, and he touched triple digits in velocity ten times.
Meanwhile, he had a groundball percentage over 50% (52.5% according to fangraphs). Thus, Jimenez looked to be the rare pitcher with the ability to be both a power-strikeout pitcher and a groundball pitcher, a combination even more appreciated in Coors Field. Needless to say, his potential seemed quite great.
Then in April and May of 2010, Jimenez appeared to break out, with a sub-1.00 ERA through April and May. Of course, if you're reading The Hardball Times, you were probably warned to be wary of Jimenez's .251 and .202 BABIP in those months, which indicated that a good bit of regression was coming.
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And boy did it come, with a 4.41 ERA in June and a 6.04 ERA in July to drive fantasy owners crazy. Still, if you kept Jimenez all year, you were probably happy with the overall 19-8, 2.88 ERA line that he put up.
Still, there are some odd things about Jimenez's year:
First of all, he increased his strikeouts, but this increase mainly came against left-hand batters (Ks have actually decrease against righties).
Second, Jimenez's walk rate remained lower than it was in 2008 for the second straight year. However, this change is also odd, as the BB rate against righties increased, while the BB rate against lefties dropped a good bit.
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Finally, Jimenez's ground ball percentage dropped to 48.8%, the lowest over the last three seasons. This appears to have been caused by the increasingly-extreme groundball splits of his pitches: against left-handed batters, Jimenez's is a terrible groundball pitcher (39.4% GB rate), while against righties he's a clear groundball pitcher (57.8%). This split was not as extreme in 2009 or 2008 at all. So what caused this?
These oddities raise the question: what can we expect from Jimenez next year? Let's look at the pitches:
What Jimenez throws
Jimenez historically has thrown six pitches - a four-seam fastball, two-seam fastball, change-up, splitter, slider, and curveball - during his career. However, he appears to have broken out a seventh pitch in 2010 - a slider. That said, the slider was barely used in 2010 (it was thrown 37 times), so its impact on Jimenez's performance is negligible and not worth any further discussion.
Other than the cutter, the movements of all six of Jimenez's other pitches remained the same in 2010. The same was true of the velocity of these pitches. There also isn't a large difference in the frequency of use of any of these pitches. No, whatever caused the odd results of Jimenez in 2010 appears to be in the location of where Jimenez threw his pitches.
Jimenez' fastball and the location changes in 2010
The key pitches, of course, when discussing Jimenez are his two fastballs, which he throws a combined 60% of the time. The two-seamer is thrown twice as frequently as the four-seam fastball against both left- and right-handed batters, but both pitches are thrown fairly frequently. The four-seam fastball is slightly faster than the two-seamer (by about 0.5 mph), has about two inches more hop ("rises" two inches more), but has around three inches less tail.
As two-seam fastballs go, Jimenez's pitch does not have a great amount of sink. However, this lack of sink is countered by the pitch's great velocity, which increases the pitch's ability to get ground balls (for more on this phenomenon, see here).
That said, it's this pitch that seems to be the greatest cause in the emergence of Jimenez's odd groundball splits and his improved ability to get strikeouts against left-handed batters in 2010. Take a look at the following table, which shows the results of these two fastballs against left-handed batters each of the last three years:
Pitch TypeYearSwinging Strike %Ground Ball %
Now, of course, the question is what caused this dramatic change in the results? The answer is where Jimenez has located his fastballs against left-handed batters. In 2009, Jimenez threw both fastballs at a higher location in the strike zone than he did in 2008, but he kept the horizontal location in the strike zone around the same location.
Higher sinkers will still get ground balls against same-handed batters, but will be less effective against opposite-handed batters: in this case, left-handed batters. Of course, high fastballs are more likely to result in swinging strikes, as well, which explains the increase in strikeouts.
In 2010, Jimenez kept his aim high, but altered his horizontal aim as well: he tried to throw both fastballs against right- and left-hand batters more away from hitters than he did previously. Against right-hand batters, this put the ball more in the middle of the zone (Jimenez had previously aimed inside on these batters). Against lefties, however, this resulted in these pitches being in the outside part of the plate more often than before.
The end result was an increase in swinging strikes (Jimenez's best spot for getting swinging strikes the last two years against LHBs has indeed been away and high). However, as you could guess from the table above, the result was a drop in the groundball rate (the high-and-in pitches did get ground balls more frequently than high-and-away pitches.)
All in all, these appear to be real changes in Jimenez's pitching habits, and we should expect the increasingly extreme K and GB splits to continue in the future.
But what about the decreased walks?
You may have noticed that the oddity regarding the reduced walks of Jimenez over the last two years is not accounted for yet in this analysis. This is because it's hard to understand why Jimenez is getting a better BB Rate. Jimenez did do a better job in 2010 throwing strikes on three-ball counts. Of course, he threw more pitches in three-ball counts in 2010 than in 2009 (and in a roughly equivalent amount to 2008), negating the effect of this improved accuracy.
Moreover, Jimenez's ability to hit the strike zone didn't seem to change against either hand too much in 2010 as compared to 2009 or 2008. One theoretical explanation you might think of is that batters were swinging more in 2010 and 2009 at pitches out of the strike zone. Indeed, Fangraphs' BIS data would tell you that was the case in 2010.
Unfortunately, this is one of those cases where the BIS data is incorrect....according to PitchF/X data, batters did not swing at pitches out of the strike zone significantly more frequently in 2010 or 2009 as compared to 2008 (For an explanation as to why BIS data is inaccurate in this area, see Colin Wyers' article here.
The end result is that, without a discernible reason why Jimenez's BB rate has dropped, don't bet on it staying as low as it was in 2009 or 2010, and don't be surprised if it returns to being above 4.0 BB/9.
Ubaldo Jimenez has tantalizing stuff. And at times he looks like an ace. But as aces go, he's a riskier proposition than other No. 1 starters for your fantasy team. This is the case for two reasons:
1. His walk rate is likely to increase in the future, resulting in his numbers not being as impressive as they were in 2009 or 2010.
2. While his changes in where he locates his fastballs have resulted in increased Ks, they also have increased the volatility of his pitch results. Because he no longer will get as many ground balls against LHBs, he's more likely to give up HRs, which will ruin quite a few fantasy starts. Jimenez had a HR/FB of 3.3% (according to fangraphs) against LHBs in 2010. That's due for a good bit of regression, especially considering he plays in Coors Field, humidor notwithstanding.
The end result is that against teams with a large amount of LHBs, Jimenez is more likely to be a feast-or-famine pitcher than he was before 2010: he could give you a start with a lot of Ks, or he could end up giving up a few gopher balls.
Thus, I probably wouldn't have Jimenez too high on your list of choices to be your No. 1 starter in your 2011 fantasy league.
Josh Smolow wishes that one day pitching coaches would seem to actually, you know, do something. You can contact him on twitter under the name garik16.
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