Coming into this year, there were three pitching prospects generally considered the best in baseball: Francisco Liriano, Anthony Reyes and Justin Verlander. With his exceptional performance this season after missing a lot of time the last two years, Cole Hamels has reinserted himself into this discussion.

First, some background and scouting on the four of them. Hamels, a 6'4", 180 lb lefty, was drafted in the first round out of high school in 2002, but didn't pitch as a pro until the following year (in A ball). His repertoire includes a fastball that tops out at about 94 MPH, a changeup that has been described as the best in the minor leagues, and a good curveball. Liriano, who's 6'2" and 200 lb and also throws left-handed, was signed as an undrafted free agent out of the Dominican Republic in 2000, and started his pro career the next year in rookie ball. He throws a fastball at up to 98 MPH and a hard slider at 91. Reyes, a 6'2" 215 lb righty, was drafted in the 15th round after four years at USC in 2003, and started in high A the same year. Reyes throws a mid-90s fastball, as well as a slider and changeup. Verlander, a 6'5", 200 lb right-hander, was a first-round draftee out of Old Dominion in 2004, and started pro ball in high A the next year. He's best known for a fastball that can reach triple digits, but also throws an above-average curve and decent changeup.

Here are some career minor league numbers for the four of them:
Pitcher   IP     ERA  H/9  HR/9 W/9  K/9
Hamels    195.33 1.43 5.25 0.09 3.32 12.59
Liriano   422.33 3.39 7.82 0.62 3.20 10.31
Reyes     284.00 3.58 7.95 0.86 1.87 10.01
Verlander 118.67 1.29 6.14 0.30 1.97 10.31

Hamels and Verlander appear at first glance to be the class of this group, with the best ERAs by far, with Verlander edging out Hamels by 0.14.

Hamels has an astonishingly low home run rate, leading the field by 0.21 HR/9. I don't know enough about the minor league parks to know if this might be park influenced, but the difference is far too great, I think, to attribute solely to park factors. Verlander is well behind Hamels in this category, but well ahead of the other two.

Hamels' also has the best hit rate of the four, besting Verlander by almost a full hit per game, and 2.5+ fewer than Liriano or Reyes.

Hamels has by far the best strikeout rate of the group, by more than 2 per 9 innings.

Walk rate is Hamels' only weakness among this competition, and it is in this category where Verlander and Reyes particularly shine. As a result of the high walk rate, Hamels' K/BB ratio is the second worst, although still a very good 3.79. Reyes and Verlander are outstanding, at 5.35 and 5.23 respectively.

The first glance, however, doesn't tell the whole story, particularly with respect to Hamels. His numbers are influenced by the fact that he has pitched a great deal at Clearwater, where, because of his health issues, he has started each of the last three seasons after demonstrating mastery of that level in his first pro season. So, let's see if we can break down the numbers and attempt to compare the pitchers level by level, and disregard Hamels' high-A performance after 2003.

Pitcher   Age Level IP    ERA  H/9   HR/9 W/9  K/9
Hamels    19  A+    26.33 2.73 9.91  0.00 4.78 10.94
Liriano   20  A+    117.0 4.00 9.08  0.46 3.31 9.62
Reyes     22  A+    36.67 4.66 10.06 1.23 1.72 9.33
Verlander 22  A+    86.00 1.67 7.33  0.31 1.99 10.88

In high-A ball, Verlander clearly had the best all-around numbers. However, he did it as a 22-year-old after three years of college, whereas Hamels was just 19 and in his first year out of high school. Hamels' hit rate and walk rate were rather high (and both were considerably higher than what he posted at Lakewood prior to his promotion), but not enough to hold him back.

Pitcher   Age Level IP    ERA  H/9   HR/9 W/9  K/9
Hamels    21  AA    19.00 2.37 4.74  0.95 5.68 9.00
Liriano   20  AA    39.67 3.18 10.21 0.91 3.86 11.12
Reyes     22  AA    74.33 2.91 7.51  0.36 1.57 12.35
Verlander 22  AA    32.67 0.28 3.03  0.28 1.93 8.82

In AA, Hamels' improved his ERA over what he posted two years earlier in high-A, despite allowing the first two homers of his career, and despite a big jump in walk rate. He did this largely on the strength of a huge drop in hit rate. Again, Verlander has the best numbers at this level.

Pitcher   Age Level IP    ERA  H/9  HR/9 W/9  K/9
Hamels    22  AAA   23.00 0.39 3.91 0.00 0.39 14.09
Liriano   21  AAA   91.00 1.78 5.54 0.40 2.37 11.08
Reyes     23  AAA   128.7 3.64 7.34 0.91 2.38 9.51
Verlander skipped AAA.

Hamels, as we all remember well, was utterly dominant in AAA, allowing just one earned run and one walk versus 36 strikeouts in his 23 innings before getting the call-up. It should be noted, however, that the teams he faced in his three AAA starts were all relatively weak offensively. Liriano and Reyes both acquitted themselves well in AAA, posting very good numbers across the board, and Verlander skipped AAA and was called up directly to the majors late last year after owning AA hitters.

Finally, let's take a look at their numbers in the majors thus far (through Sun. 5/21).

Pitcher   Age Year IP    ERA  H/9   HR/9 W/9 K/9
Hamels    22  2006 11.33 3.18 4.77  0.79 7.15 9.53
Liriano   21  2005 23.67 5.70 7.23  1.52 2.66 12.55
Liriano   22  2006 27.33 2.96 9.55  0.33 2.31 12.18
Reyes     23  2005 13.33 2.70 4.05  1.35 2.70 8.10
Reyes     24  2006 11.33 3.18 4.77  0.79 7.15 9.53
Verlander 23  2005 13.33 7.15 11.91 0.79 3.97 5.56
Verlander 24  2006 51.00 3.18 8.12  1.06 2.47 4.76

All except Verlander have posted numbers in the majors that are predictable based on minor league performance. Verlander was hit pretty hard in his few innings last year, but has done much better so far this year, albeit with mediocre strikeout and walk rates. Hamels has done well so far, but really needs to cut down on the walks.

Setting health issues aside for the moment, based on these numbers in total, Hamels may not be the best prospect of this bunch, but he's damn close. The only thing that will hold him back is walk rate, although his AAA performance might be indicative of some improvement in that regard. Interestingly, aside from AAA, Hamels' walk rate has jumped with each promotion, from 3.01 (A-) to 4.78 (A+) to 5.68 (AA) to 7.15 (MLB).

One thing that I wonder about regarding Hamels' strikeouts and walks is whether his phenomenal strikeout rates and somewhat high walk rates have been achieved by nibbling around the corners and frequently missing, but getting weak minor-league hitters to chase anyway. His early MLB performance seems to support this theory. If so, this might portend trouble for him in the majors unless he can improve his control.

Taking health into account, this is a tougher race to call. Hamels probably drops a slot or two, although Reyes has also had injury problems and Verlander has been cited for mechanical issues which might cause him trouble down the line. Liriano seems to have been uniformly healthy, but he's also the second-youngest (two months older than Hamels) and has pitched the most professional innings of the group.

Regardless of how you rank them, I can't see how Hamels, assuming good health, could project as less than a top ace. Not that he'll be one this year (or ever, if he can't stay healthy), but his numbers veritably scream "ACE," especially if he improves his control, as one would expect a young pitcher to do.