This season, Roy Halladay, dominated batters to the tune of a 17-10 record and 2.79 ERA.  In a stellar 2008 campaign, the Doc won 20 games with a 2.78 ERA.  Three seasons ago, back in 2007, Halladay posted a 16-7 record with a 3.71 ERA.  He went 16-5 in 2006, when his ERA was 3.19.  If Halladay places in the top 5 in 2009's Cy Young Award voting, it would be for the fourth consecutive time (and if Kevin Mench hadn't done his first disservice to Blue Jays fans in 2005, it would almost certainly be his fifth).  And yet, the 2006 Roy Halladay was not the same as the 2009 Roy Halladay.  As good as Doc was back in '06, he's even better now.

In 2006, Halladay was an absolute groundball-inducing machine.  57% of batted balls were grounders, third in the AL.  In 2009, Halladay's groundball-rate fell a bit to 50.2% -- still good for 4th in the AL and 15th in the majors.  So Halladay hasn't induced quite as many grounders as he did four years ago, but he's still pretty good at getting them to hit the top half of the ball.  Halladay's infield-fly (pop-up)-rate was 13.8% in 2006 (third in the League).  His mark of 12.5% in 2009 placed him fifth.  Again, not getting quite as many pop-ups, but he's still among the best.  In 2006, Halladay walked 34 batters over 220 innings (1.4 BB/9, second in the AL).  In 2009, Halladay led the AL with 1.3 BB/9.  Still similar.  But here is where the similarity stops.  In 2006, Halladay struck out 132 batters (5.40 K/9, 26th in the AL).  In 2009, Halladay struck out 208 batters over 239 innings (7.8 K/9, 8th in the AL).  How much of a difference do two or three strikeouts a game make?  Well, in Halladay's case it seems like the difference between an FIP of 3.60 and an FIP of 3.06, corresponding to a difference of about 1.5 WAR, according to Fangraphs.  The difference between Roy Halladay and C.C. Sabathia this season was about 1.3 WAR.  Roy Halladay was signficantly better than C.C. Sabathia this season.

So how does an already-excellent pitcher make himself even better?  It seems that the underlying cause is his increased reliance on the cut-fastball.  Since first using the pitch about five years ago, Doc has been working it into his repertoire more and more -- throwing it more than 40% of the time in 2009 (up from just 19% in 2006).  Throwing more cutters has led to fewer fastballs (52% in 2006, 47% in 2007, 41% in 2008 and just 32% in 2009).  As Doc's fastball is generally of the two-seam variety, it should come as no surprise that his increasing reliance on the cutter would result in missing more bats (80.4% contact-rate in 2009 vs. 82.9% contact-rate in 2006) but would also result in fewer ground balls.  It remains to be seen whether Halladay will throw even more cutters in 2010, but if recent history is any indicator, there is a definite trend.