Fantasy fallout: Ryan Dempster re-ups with Cubs

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Ryan Dempster took a big step forward in 2008, but can he sustain that level of performance in 2009? (Icon/SMI)

The first big free-agent signing of the off-season occurred yesterday as Ryan Dempster re-upped with the Chicago Cubs for 4 years and $52 million. Dempster moved to the rotation in 2008 after spending four years as a reliever and was tremendous with a 2.96 ERA. Here was his full fantasy line:

+------+------+-------+----+------+------+-----+----+
| YEAR | TEAM | IP    | W  | ERA  | WHIP | K   | SV |
+------+------+-------+----+------+------+-----+----+
| 2008 | Cubs | 206.7 | 17 | 2.96 | 1.21 | 187 |  0 |
+------+------+-------+----+------+------+-----+----+

Let’s look a little deeper to see what we should expect in 2009.

Numbers

If you’re new to THT Fantasy Focus and are unfamiliar with LIPS ERA, K/BB RI, or any of the other stats I’m using, check out our quick reference guide. These stats provide a much clearer picture of a player’s talent, so it’s well worth taking a couple of minutes to learn them.

+------+-----+----+----+-------+------+----------+-----------+------+------+---------+------+
| YEAR | AGE | G  | GS | IP    | ERA  | LIPS ERA | DIPS WHIP | K/9  | BB/9 | K/BB RI | xGB% |
+------+-----+----+----+-------+------+----------+-----------+------+------+---------+------+
| 2004 |  26 | 23 |  0 |  20.7 | 3.92 |     3.98 |      1.50 | 7.84 | 5.66 |   -0.13 |   53 |
| 2005 |  27 | 63 |  6 |  92.0 | 3.13 |     3.46 |      1.43 | 8.71 | 4.79 |    0.22 |   58 |
| 2006 |  28 | 74 |  0 |  75.0 | 4.80 |     4.40 |      1.48 | 8.04 | 4.32 |    0.18 |   50 |
| 2007 |  29 | 66 |  0 |  66.7 | 4.73 |     4.19 |      1.38 | 7.43 | 4.05 |    0.06 |   48 |
| 2008 |  30 | 33 | 33 | 206.7 | 2.96 |     3.87 |      1.28 | 8.14 | 3.31 |    0.35 |   49 |
+------+-----+----+----+-------+------+----------+-----------+------+------+---------+------+

While Dempster’s 2.96 ERA was somewhat lucky, his 3.87 LIPS ERA shows that he did have a legitimately good season. A .288 BABIP, 77 percent LOB%, and a 7.7 percent HR/FB all helped his actual ERA to be nearly a full point lower than it would have been with neutral luck, but his strikeout, walk, and ground ball numbers were all very solid.

While this is a great sign for 2009, we need to be very careful not to get too enamored by Dempster’s 2008 season and ignore the previous years, which were generally worse and came in relief innings. In fact, there are quite a few things that could give us pause in projecting an equally good season for Dempster next year.

The fact is, 2008 was one of the best year’s of Dempster’s career. His strikeout rate was higher than it’s been in every year except 2000 and 2005 (when he was in the bullpen), and his walk rate was the lowest of his career. Where did that come from…and at the age of 30?

Looking at Dempster’s PITCHf/x data, he doesn’t seem to have improved any of his pitches. His fastball was still good, his change-up was still very good, and his slider was still kind of crappy. He did use the slider less frequently than in year’s past, which likely helped to some degree, but there was very little overall change in Dempster’s physical skills. Perhaps we’ll do a more in-depth look at some of the mental pitching skills sometime in the near future.

There was a discussion at The Book Blog yesterday about the possibility of Joakim Soria moving to the rotation which can be applied to Dempster’s move this past year. Quoting Tom Tango, “the rule of thumb is to add 1 run to convert to a starter (not a hard and fast rule).” While this isn’t an absolute measure (as Tango noted), let’s take a look at what Dempster’s 2004-2007 LIPS ERA would look like if we applied this rule:

+------+-----+----------+
| YEAR | AGE | LIPS ERA |
+------+-----+----------+
| 2004 |  26 |     4.98 |
| 2005 |  27 |     4.46 |
| 2006 |  28 |     5.40 |
| 2007 |  29 |     5.19 |
| 2008 |  30 |     3.87 |
+------+-----+----------+

I also included his actual 2008 LIPS ERA (no adjustment needed since he spent the season as a starter) for easy comparisons. Here, we see that Dempster far exceeded what we would have expected for him at the start of the season. He jumped a full 1.32 points of ERA from 2007 to 2008 and 1.53 points from 2006. Those are huge numbers, and it makes me wonder — at the very least — how repeatable his 2008 line will be.

Finally, I’d like to take a look at some of the cool new plate discipline stats up over at FanGraphs.

+------+-----+------+------+-----------+----------+-------+
| YEAR | AGE | K/9  | BB/9 | F-Strike% | O-Swing% | Zone% |
+------+-----+------+------+-----------+----------+-------+
| 2005 |  27 | 8.71 | 4.79 |      55.1 |     22.4 |  47.2 |
| 2006 |  28 | 8.04 | 4.32 |      59.4 |     22.7 |  50.7 |
| 2007 |  29 | 7.43 | 4.05 |      57.8 |     31.7 |  46.9 |
| 2008 |  30 | 8.14 | 3.31 |      57.8 |     28.5 |  49.4 |
+------+-----+------+------+-----------+----------+-------+

Eric Seidman recently posted an article with correlations for these stats. Here are the results we’re interested in:

+------+-----------+----------+
| Stat | F-Strike% | O-Swing% |
+------+-----------+----------+
| K/9  |      0.19 |     0.28 |
| BB/9 |     -0.72 |    -0.49 |
+------+-----------+----------+

Essentially, F-Strike% (which is how often the pitcher gets a first-pitch strike on the batter) predicts walk rate very well and strikeout rate decently. O-Swing% (which is how often the pitcher induces swings on pitches outside the strike zone) predicts walk rate pretty well and strikeout rate moderately well.

If we look back up at Dempster’s stats, though, we see that his F-Strike% didn’t move at all from 2007 to 2008 and is right in line with his four year average. His O-Swing% actually decreased from 2007 to 2008 (though it was still better than 2005 and 2006). So while Dempster’s K/9 and BB/9 both got better this year, these stats really don’t support such drastic improvements.

I also included Zone% (which is simply how often the ball is thrown in the zone), which I assume correlates relatively well with walk rate since you can’t walk a batter if you never throw outside the zone. This did improve from 2007, but it was worse than 2006 when Dempster posted a BB/9 a full-point higher (albeit with a lower O-Swing%).

Concluding thoughts

Overall, we have to give Dempster credit for what he did in 2008, but we must also use this information in conjunction with what he’s done in the past and with what some of the underlying indicators suggest.

I would be much more comfortable putting Dempster down from something like a 7.8 K/9 and 3.8 BB/9. This, in conjunction with a 50 percent ground ball rate, would still allow Dempster to post an ERA in the low 4.00s. Just make sure you aren’t fooled by that 2.96 ERA or even the 3.87 LIPS ERA, because the odds seem to be against a repeat of either.

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