I put together some stats that I think will be fun (I think "useful" would be taking things a bit too seriously) for prospect watchers and we TwinkieTown top-25 voters this offseason. For prominent young Twins position players, I calculated their overall age relative to league over the course of their careers (in table below as AgeL) and compared that to their career stats.
So the method is this: I started with a pure assumption on my part that a "natural" prospect progression is like this:
The player will be age 19 in the Gulf Coast League,
20 in the Appy League
21 in A
22 in A+
23 in AA
24 in AAA
and 25 in MLB.
Each player is measured against that baseline and how much younger they were than those figures. So Aaron Hicks, e.g., has been on average 1 year younger than his league, compared to the numbers above, so he has an AgeL of 1. Josmil Pinto has been on average 0.2 years older than his league, so he has an AgeL of -0.2. See, sort of fun. All stats are weighted by plate appearance and incorporate both MiLB and MLB stats.
For me, it helps contextualize our prospects' performances against each other, but also helps with comparing prospects with young MLB guys like Hicks and Arcia who no longer quality for prospect lists. Here's the list, sorted by overall offensive performance relative to league, measured by wRC+ .
For instance, I think it's interesting that Arcia is so close to Buxton and Sano not just in overall offensive performance, but in terms of age also. Despite not having a really flashy rookie year, he's clearly still a guy to expect a lot from given how much he has accomplished and how fast. Hicks has a somewhat similar story to tell. Guys like Adam Walker on the other hand maybe don't look as impressive despite some good offensive numbers when you consider that, say, Chris Parmelee has averaged about the same production relative to league while being, on average, a full year younger than Walker.
Maybe it would be fun to do a Top-10 Under 25 for the site in addition to the prospect list? I think that sort of list is generally even more interesting than the pure prospect lists.
(full disclosure: the stats and ages above are as of 9-24-2013 when I pulled these stats. That leaves out only about 1 week of the season)