I have Jon Niese fever.
He's entering his age 25 season, coming off a 2011 with a 19.9 K% a 6.3 BB%, and a 51.5 GB%. It's a thing of beauty, really-- seeing those factors all aligned at a very common 'peak' age. There is a quietly robust kinetic quality to it all.
Obviously, being poised for a break-out and actually breaking-out are separated by a continent of x-factors, and estimating such a jump based off of just 4 values is absurd, but just play along for a moment.
Take a glance at starting pitchers with similar numbers* since 1992 in at least their age 24-26 season, and how they fared immediately afterward.
*with K% 18-22, BB% < 7, age 23-25, > 125 IP
Not a bad list, am I right?
Starting from the top we see all-star after all-star until we hit Glendon Rusch. Rusch did flash these signs of breakout potential in two back-to-back seasons early in his career and then quickly receded into the shadows of history. Andy Benes continued to post good but never great numbers, he did break-out, so to speak, much later at age 29 with a +5 WAR season. Eric Milton and Steve Woodard's seasons were undoubtedly their respective peaks, and probably are a good indication of what Niese's floor looks like.