I don't know. Ha!
But it has been a topic of conversation lately, and I always miss it in the main threads because I'm out doing things when they happen, and people have moved on by the time I show up. I don't pretend to have any unique insight, but I DO have a Baseball-Reference Play Index subscription, and I love playing with it. So this is just for anyone who wants to know.
I did a sort in the above mentioned play index to find players who would be good investments from 28-32 (i.e., Cain's age if he signed a 5 year contract at the end of this year). I put a bottom limit of 20 WAR - averaging 4 WAR per year or above over the course of a five year contract seems like a decent investment. Rather than go with the large list of players who topped that since 1901 (73, if you're wondering), I limited it to players who fit the sort from 1990 on. 'Cause, you know, I'm not made of time. This list of "good investment" pitchers came out to 15. Going from most recent on down:
Then I did a sort to find players who put up better than 20 WAR through age 27. In other words, pitchers who were young and effective (like Cain). The idea is to see if putting mileage on those young arms produced a lot of blowouts. Some on the above list won't show up on this list due to a late peak (I'd be looking pointedly at Randy Johnson here, but, ew). In this sort I limited the years from 1984 onwards, to make sure I caught anyone from the prior list that played in the 80's, but cut off anyone who turned 27 prior to 1990. This list had 32 pitchers.
Showing up on both lists we find, again from most recent on down:
So, those are the success stories. The others include guys who had great careers so far, but haven't reached or finished the 28-32 part of their careers:
Those plus the 6 from before gives us 16 of the 32. The rest:
Johan Santana (missed the first list by .9 WAR)
We can’t quite say half the guys on the list are busts, because several of those guys would have been, if not great investments, at least not disasters. Johan Santana, Tim Hudson, Andy Pettitte, Kevin Appier, Andy Benes and Bret Saberhagen would have all brought at least a fair amount of on the field value during the hypothetical 5 year contract. Most of the rest I’d probably consider a clear bust if given a fat contract from age 28-32, although some would have shown clear warning signs well prior.
For your perusal, in case you like to goggle at such things the way I do, I present both lists. I’m including all the data back to 1901, just in case you’re curious. First, the youngsters:
And the 28-32 crowd:
Feel free to point out whatever I may have missed.