When it comes to baseball prospects, age versus level is a handy, shorthand way to evaluate them. Once they reach the big leagues, contact rates and batted-ball tendencies are maybe the most useful data sabermetricians have turned out since the turn of the century.
All along, it's important to keep track of which players have substantial upside. That is, which can still improve substantially from here.
A prospect given no leeway or benefit of the doubt will be forever misunderstood and underrated. Every baseball player comes to the show with something meaningful yet to learn or with growing left to do. No one peaks, in an absolute sense, at age 23.
Ay, but there's the rub!
Simultaneously, there are a handful of young athletes every season in MLB from whom too many expect too much, simply because those guys are young and have not yet had a chance to fail. Omne ignotum pro magnificum.
It is often too tempting too dream on a guy's ceiling, rather than coolly weighing his upside against his risk of flame out or of simply settling in as a useful non-superstar.
In that spirit, here are five players whose ceilings might be lower than many imagine.