Polanco's under-the-radar rise

Finally, he's here.

Heads exploded in anticipation of the arrival of Gregory Polanco in the big leagues. The do-everything, 22-year-old prospect, armed with a seemingly limitless array of talents, has been more frequently discussed than most members of the Pittsburgh Pirates' big league roster this year while posting a .347/.405/.540 line with 15 stolen bases for Triple-A Indianapolis.

Yet the conversation about his potential and big league readiness, as well as the Pirates' deliberate approach to calling him up -- which didn't happen until a Neil Walker appendectomy forced their hand on Monday night -- obscured a fascinating part of Polanco's emergence as a top prospect. There was a time, not long ago, when he was a minor leaguer of no profile whatsoever.

Players who emerge as elite prospects usually take little time to announce themselves. After all, part of achieving top-prospect status is the ability to stay ahead of the development curve at every step and to assert game-changing ability at virtually every level.

But while Polanco has enjoyed a meteoric ascent in racing from low Class A to the big leagues since the start of the 2012 season, his track record prior to that resembles that of few top prospects in recent years.

"It certainly is rare," noted Pirates assistant general manager Kyle Stark. "[But] there's a lot of things about Gregory that are unique."