That's fine, but the Bill James number was derived in the 1980s. It's hard to get an accurate look at prime right now, because right now is always changing. I happen to believe that there are a couple of factors at work right now (the weeding out of PEDs, the increased emphasis on defense) that are shoving it a little earlier than usual. I mean, the real answer is that a baseball player's value comes from an odd mix of disparate skills that all have different age curves, and every player possesses those in different mixes. And really, none of it matters because as I mentioned earlier, age curves for established MLB players suffer from huge survivor's bias issues and don't necessarily apply to prospects and non-established players. But that's a tangent to a tangent. i'm all for challenging the orthodoxy, but if you're going to try to slay the beast, you better bring it. i mean, with something more then a hubristic maelstrom of keystrokes survivor's bias? hilarious. all you're actually doing is polluting the sample population with irrelevancy. the age curve of a [expletive] prospect doesn't matter, it has nothing to do with anything. if i was trying to figure out the ideal age range to be a kickass president of the united states, i wouldn't include secretaries of state in my sample. likewise, if i'm trying to find the average peak performance age range for a major league baseball player, i wouldn't include non-major league baseball players in my sample. the information wouldn't provide me a meaningful answer. furthermore, you're right that your contention that "disparate skills all have different age curves" doesn't matter, but like most other things, you're wrong in your reasoning. it doesn't matter because it's a useless conceptual framework. let's take this multi-faceted thing we call defense. defensive performance is informed by physical ability (speed, strength, agility), learned physical skill (throwing accuracy, ball handling, footwork, etc.) and, for lack of a better term, IQ (situational awareness, mental acuity, adaptable decision-making, essentially a mix of capacity and learned mental abilities). the latter probably has a positive correlation with increasing age, though, it doesn't have to. learned physical skill can withstand immediate declines in physical ability and even conceivably negate the effect of marginal reductions in physicality. physical ability will peak at a certain age and begin to decline at an increasing rate over time. physical ability will vary amongst different individuals because that's life, and thus the age curve will be steeper for some, shallower for others. either way, it's the most impacted by time. so what's my point? other than you're full of [expletive], it's that you're trying to inject this notion of chaos into a relatively knowable and measurable reality. at the end of the day, we can take any variety of performance measures and compare them with age and the end result is our performance age curve. if our sample is meaningful, then our answer is meaningful. lastly, to argue that reduced use of PED's and an emphasis defensive performance (presumably at the expense offensive performance) has shifted the performance peak younger is kylejrm. my apologies to the uninitiated, but "kylejrm" is shorthand for "intellectually dishonest at best". ped's are a technology, and not a monolithic one at that. the reign of designer PED's is now, and they're better than ever. you know what also is a technology? astroturf. there used to be a lot of it around in the 70's and 80's, and it sped physical declines. training regimens are a technology. and they were essentially nonexistent prior to the late 80's/early 90's. now they're regular practice, and assuredly allow players to maximize their physical peak and marginalize declines. technology is constantly improving our ability to push these limits. and regardless of any perceived emphasis on the value of defense and its impact on this discussion, the DH still exists. in fact, we just added another one for this season. so yeah, there's that.