about a week ago, baseball america put out its list of the top 50 prospects in baseball at midseason 2012. the cardinals made out like bandits, landing 4 names in the top 50: oscar taveras at 18, shelby miller at 20, carlos martinez at 26, and kolten wong at 44.
other sources put out similar rankings at midseason. john sickels named the same four in his top 40, with taveras at 9, martinez at 24, wong at 29, and shelby miller at 35. sickels' longer list put trevor rosenthal and tyrell jenkins together at 88 and 89, with matt adams making at appearance at 100.
it's easy to get excited about these prospects. this is an exciting group of players, getting increasingly close to the majors. but it's also easy to get too excited, to expect too much.
i'd like to take a quick look at former top prospects and how they performed to think about how to measure expectations.
in 2009, BA ranked the following players in their top 20 overall prospects (with their cumulative fWAR in parentheses):
1. matt wieters (10.8)
2. david price (12.5)
3. colby rasmus (10.4)
4. tommy hanson (9.4)
5. jason heyward (10.7)
6. travis snider (1.7)
7. brett anderson (7.5)
8. cameron maybin (7.1)
9. madison bumgarner (9.3)
10. neftali feliz (4.4)
11. trevor cahill (6.8)
12. pedro alvarez (2.8)
13. mike moustakas (3.7)
14. buster posey (7.7)
15. dexter fowler (7.4)
16. giancarlo stanton (10.4)
17. lars anderson (-0.3)
18. logan morrison (2.8)
19. alcides escobar (4.9)
20. gordon beckham (5.1)
that's a pretty compelling list. i don't know that you'd call many of those picks flops: lars anderson sure doesn't look like a prime prospect. without knowing the jays system well, it looks like travis snider suffers from a mix of tough competition in the outfield, some injuries, and some underpeformance (a 67 wRC+ last season). and, despite his success on the twitter pro circuit, logan morrison is a pretty underwhelming top 20 prospect after almost 1100 PAs.
but i think you could fairly call this an 85-90% success rate for the top 20 prospects. that's pretty heartening as a factoid. seeing taveras and miller ranked in BA's top 20 puts them in pretty elite company.
saying that cumulatively, four years later, these prospects are successes doesn't tell the whole story. some of these prospects, when looking at their careers in depth, had a less-than-smooth transition to the majors.
take cameron maybin, for instance. he bounced up and down from the minors to the majors over the course of three seasons, accumulating 1.6 wins over 288 major league PAs. he got something like a real chance in 2010, amassing more than 300 PAs, but accumulating only 0.7 WAR in that time, and showing off an underwhelming 80 wRC+.
only in 2011 did he play up to his potential, putting together a 112 wRC+, for a total 4.7 WAR. so far this year, he's back at a replacement value level, with a 75 wRC+ (albeit with a .261 BABIP).
pedro alvarez has shown similar year-to-year inconsistency. he hit for a 112 wRC+ in 2012 and 110 this season, but in between, he hit for an appalling 57 wRC+ in his sophomore year.
and no accounting of prospect inconsistency would be complete without acknowledging ex-cardinal colby rasmus, whose 89, 129, 90, 119 wRC+s over the last three and a half seasons are the most familiar struggles of a top prospect.
while the top 20 was remarkable for its level of success, the next 20 were a lot shakier. while ranks 21-40 featured some all-stars (andrew mccutchen, austin jackson, and elvis andrus), the later range featured a lot of prospects who, if they have not emigrated to bust-land, are definitely showing their papers at Immigration and Customs. mat gamel, brett wallace, fernando martinez, and justin smoak have been worth -1.2 WAR over their collective careers. matt laporta has been worth -1.5 wins over 1000 PAs just by himself.
so, while the top 20 is full of pretty sure things, later ranks can hold a range of prospects, from busts to stars.
roughly eyeballing the 2008 list indicates that this is about par for the course. a few more busts in the top 20 (snider, brandon wood, jake mcgee, fernando martinez, franklin morales).
one of the things which surprised me, as the opposite of what i expected, was that the OLDEST prospects on the 2009 list were the ones with the biggest struggles in their big league transitions: alvarez, lars anderson, and maybin were 22, and morrison and snider were 21. by contrast, the 19-year-olds in the top 20 were very successful in their transitions: heyward, stanton, and bumgarner. i had expected to find the opposite - that the younger prospects tended to struggle more because they were rushed or lacked seasoning.
but perhaps the most important thing to remember is that the course of prospectdom does not necessarily run smooth. having a down year is not a reason to panic or to throw in the towel on a prospect. instead, these down years can be part of the learning curve.
while there's good reason to expect that taveras or miller or carlos martinez will come up and be successful, they may not be successful immediately, and their success may be staggered with periods of real struggle. fans and the team need to temper their expectations for prospects, so that ordinary setbacks don't meet with unreasonable levels of disappointment.