as chances increase that the cardinals will look for a starter to shore up the rotation, i think it's worth taking a look at members of our current and (hopefully) future rotations.
one of the stranger aspects of our rotation is that our starters are exceptionally slow pitchers: jake westbrook has the second fastest fastball of any of our starters at 90.0 mph; kyle lohse and kyle mcclellan are in the bottom fifth of all qualified starters for fastball speed at 89.0 and 88.8. jaime garcia comes in at 89.7. only chris carpenter appears outside the lowest third of all starters for velocity, with a very respectable 92.4 mph. of course, it goes without saying that this speed deficit comes in part as a result of the injury to adam wainwright (career FB velocity 90.6).
the cardinals rotation has an overall fastball velocity of 90.1, good for 23rd in the majors. speed is not the only way to be an effective pitcher: shaun marcum, carlos zambrano, jered weaver, and jair jurjenns all have sub-90 mph offerings. obviously, one can be a good pitcher without a blazing fastball. still, the five most effective rotations by WAR all fall in the top 17 rotations by velocity. it is very hard to put together a good rotation without some power pitchers in the mix.
that velocity deficit is one of many reasons why it is exciting to see prospects like shelby miller and carlos martinez coming up through the system. the idea of having two solid pitching prospects throwing in the mid- or even high-90s could really change the nature of a rotation currently built to generate groundballs. it is exciting, obviously, for any team to have a #7 and #18 prospect in the midseason top 50 rankings by baseball america, regardless of how hard they throw or how hard current members of the rotation throw. the fact that these rising prospects are hard throwers is simply an added benefit. a rough eyeball of the rankings reveals that only top-notch systems like the braves', the rays', and the rangers' farms have two prospects in the top 20 of the list.
it would also be incomplete not to note that the farm is increasingly full of other hard throwing starting prospects (some of which may appear as relievers): maikel cleto famously touches 100 mph; lance lynn is showing off a 92+ mph fastball at the major league level, albeit as a reliever; adam ottavino could be an effective starter or, more likely, reliever should he discover some control; jordan swagerty, joe kelly, and several other serious pitching prospects round out the low minors. the prospect of a younger, cheaper, harder-throwing rotation in the near future should make any cardinals fan happy.
the weak links of the current rotation are almost certainly kyle mcclellan and jake westbrook. there has been some debate about whether, assuming the cardinals acquire a starter, kyle or jake should go to the bullpen.
at the outset, one should admit that westbrook has the non-statistical edge of making $8m this year, $8.5m next, with a similar mutual option for 2013, including a $1m club buyout. yes, that is a sunk cost. however, baseball clubs are not in the habit of ignoring those sunk costs. contrasting a starting pitcher owed more than $10m by the club and a club controlled pitcher making less than $2m this year, and likely $3-4m next, most clubs would err on the side of keeping the more expensive pitcher in the rotation.
mcclellan has a 4.24 ERA, a 4.72 FIP, and a 4.19 xFIP, registering at exactly replacement value for the club. he strikes out a paltry 4.42 batters per nine, but walks a reasonable 2.86 batters per nine. he has allowed 13.0% HR/FB. ZIPS projects him for a 4.20 FIP the rest of the way; i suspect that may be generous. to the extent that his projection relies on his superior strikeout rate as a reliever, there's no reason to expect him to regress to the same strikeout level. as a reliever pitching in short stints, he threw his fastball at 91+ mph; as a starter, he sits around 89 mph. i am also concerned that the 13.0% HR/FB rate may not represent an unsustainable trend, for similar reasons. while one should normally expect ordinary luck to give a pitcher a roughly 10% HR rate, there is some skill in the mix. anecdotally, mcclellan periodically lobs some real meatballs over the plate; it would not be surprising that kyle should expect an above average home run rate, based on his weak velocity and propensity for throwing bad pitches. the best thing i see on kyle's side is his decent control; his walk rate of 2.86 BB/9 seems sustainable and could make a respectable groundball rate (53%) stand up, especially if the cardinal defense behind him improves. still, kyle has a fairly narrow window between his upside and downside, mostly focused around replacement value; if all goes right, he could hover around a 4.10 or 4.20 FIP; if he keeps giving up homers and doesn't strike people out, he could end up more in the 4.50-4.70 range.
jake westbrook has a dreadful 5.34 ERA, 4.48 FIP, and a 4.06xFIP. he strikes out a marginally better 4.79 batters per nine. he has chipped away slowly at a terrible walk rate, but still gives away 3.69 free passes in nine innings. he also carries a 13.2% HR/FB rate (which, like mcclellan's rate, may not be exclusively bad luck, considering westbrook's 12.1% career HR/FB rate). ZIPS projects him for a 4.06 FIP the rest of the way. the best things one can say for westbrook are that he has a track record of better performance, especially as to his walk rate, and that he still maintains an outstanding GB rate (61.0%), trailing only charlie morton among qualified starters. i have some concern, given westbrook's still recent injury history, that his control may be affected by lingering elbow issues. i suspect his ZIPS projection may be generous as well, based on his propensity for the long ball, and concerns that he may not regress to career norms on his walk rate.
while i like lance lynn and suspect he might provide a modest upgrade over either kyle or jake as a starter, i readily admit that, based on his limited major league exposure, that's a fairly speculative conclusion. i do not blame anyone in the club for not wanting to upset the rotation's apple cart at the moment for what would likely be, at best, a limited improvement. i do think it is worth continuing to watch lance's performance in the majors and look for signs of breakdown or fatigue from jake or kyle. later in the season, the case for putting lynn in the rotation may become more compelling.
i think that by most measures, jake is more likely to provide value than kyle in the rotation. neither of them seems likely to beat replacement value by much this season, absent a monster second half (like the one westbrook had last year). it would not take much to improve on either of them. given that we are paying them almost $10m put together, and have 3 runs above replacement between them, the club demonstrates again that paying large sums for modestly talented pitchers is generally not a good investment. the prospect of seeing the younger players listed above join the rotation (as well as the rumored extension for jaime) should do a great deal to limit our exposure to the risk and expense of future lohse- and westbrook-type deals