What does a historical valuation of top prospects tell us about the current Yankees crop?

In four weeks, the 2014/15 Major League Baseball offseason will move into the past, thankfully. Baseball will be brought back into the present with pitchers and catchers reporting, marking the start of spring training as it does every year. Another annual baseball tradition to look forward to in late February, one for the future, is the release of the Baseball America Top 100 Prospects list for 2015. We already have their Top 10 Yankees Prospects, but it should be interesting to note how many of the Yankee ten make the Top 100, and where they place.

Yankee fans will probably have opinions on where they choose to place franchise blue-chippers like Luis Severino or Aaron Judge on there, and we probably won't all agree. Which will be fair enough, of course, considering the editors of BA themselves require hours of debate when forming the list in the first place. Turns out, despite a mountain of available minor league/high school/college/foreign league information on each player, along with their wealth of scouting experience, attempting to project the future is hard. Who knew?

Still, if we want to try predicting the future of our prospects anyway, Baseball America is about as respected a reference as we're likely to find freely-available, short of working inside an MLB scouting office. Helpfully, there has been some interesting research on how successful the 25-year history of the Baseball America prospect lists have been in predicting major league careers. Victor Wang's model from 2008 is probably the most widely referenced here. He broke down the list of prospects who made at least one of the first 10 Baseball America prospect reports by hitters and pitchers, as well as by place on the list.  Wang compared each category to the surplus value generated by each player during their six years of team control, using wins above replacement and mass-estimates of arbitration salaries, I'd definitely recommend a read if you would like a proper look at the maths behind this, as well as a glance back at some retro-sabermetrics.

Kevin Creagh and Steve DiMicelli adapted this method, first in 2012, and then updated it last December.  The more recent of the two links has a 12 year sample of prospect lists, from 1994 to 2005, along with up-to-date WAR calculations for the six year team control on each, as well as a track on percentage of 'busts' - players who racked up less than 0.5 WAR a year. Their breakdown in table form is below, via Dave Cameron, who adds interesting analysis comparing pitcher prospects in the top-10 spots - sample size alert only 18 in 12 years - with elite established arms.

Indeed, major league performances of both hitters and pitchers ranked in the Top 10 are generally encouraging. It's worth noting that the WAR figures above are all discounted to about 82% of the raw six-year totals towards estimating 'present value of performance'. I'm linking the full article a second time here, so you don't have to scroll up to check out the methodology, I firmly believe it is worth a full read. Meanwhile, back to the prospects in the Top 10, who unsurprisingly tend to do well, it's the rate of success particularly with highly-rated pitching prospects that caught me by surprise. Good news then that Masahiro Tanaka ranked fourth last year, though we already know Tanaka is a stud when healthy.

Really, I'm more interested in the second half of the list, ranks #51 - #100. Since we won't have the new Baseball America list for another four weeks, for now consider the MLB prospect list from the end of 2014 as a benchmark, though it's worth noting that MLB does have some differences to BA - it ranks Gary Sanchez as the franchise's second best prospect for example, and Judge fifth. On the MLB list, again Severino is the Yankees #1 prospect, #62 overall. As we can see above, the 'bust' rates for prospects ranking below #50 are much higher than the elite prospects. Two-in-three pitching prospects here average 0.5 WAR or less in their six years of control, half of them are below-replacement players. Hitting prospects from the second half of the list do have better overall performance but not strikingly. While having a Yankee prospect make the Top 100 in all of baseball could be exciting, historically players at the bottom of those lists more-often-than-not do not even become average (~2 WAR/year) big-league contributors.

It almost goes without saying, except I'll say it anyway, I'm not using the above to suggest Severino will be a bust, or Judge, Sanchez, Ian Clarkin or any other current Yankee prospect. These are historical trends, about a sample of prospects, and Luis Severino is one pitcher who is not a direct part of this sample. It's also worth noting that Baseball America has a strong track record of identifying pitching prospects, elite starters are almost always found on these lists. More so than hitting prospects, where familiar faces Robinson Cano and Brett Gardner were never Top 100 prospects. It's certainly better for Severino to be ranked in the Top 100, both intuitively and historically, than it would have been if he wasn't a rated prospect. Continuing the string of obvious declarations, it would simply be better still should he be rated in the Top 10, which is highly unlikely this time around. Considering his age, there is obviously time for him to move up the list.

What we have seen historically is that apart from the most elite handful, individual prospects are at best coin flips to have successful major league careers. I think it likely that the 2015 list will have similar patterns to the above, among the 100, though we'll have to wait till 2021 to find out for sure. This uncertainty is why looking to land high-end established talent like Cole Hamels or Stephen Strasburg will involve more than one Top 100 prospect going the other way. It's also why statistically speaking such a move could well be worth making.

In any case, this doesn't in any way lessen the importance of the farm system as a whole, developing cheap, controllable talent in-house is the lifeblood of any MLB team, even one with the financial clout of the Yankees. Improving the depth in the organisation gives the Yankees more coin-flip opportunities of course, and more tradable assets as well, which is why the positive direction of the organisation here bodes well for the future of the franchise.