Like Chris Flexen, Nick Grant, the Mets' 15th-rounder, is a prep righty from without a ton of physical projection. He's already pretty mature at 6 feet, 1 inch and 206 pounds, so you wouldn't expect him to add much in the way of velocity. Despite that, there are some mysteries concerning his current stuff. Most reports have pegged Grant's fastball in the 89-91 range, though some recent reports have suggested that he's hit 97. I'd be very surprised if that were the case--it's rare to see a velocity spike that drastic, especially in a guy without a ton of size, and you'd think some other team would have nabbed him earlier if true. Whatever the speed of his fastball, he also shows a potentially above average mid-70s curve and some feel for a changeup.
Mechanically, I've heard mixed things. He seems to have many of the same issues Flexen does. He's aggressive in driving off the rubber, but that also means his body gets in front of his arm before release, adding effort to his delivery. The elbow also tends to rise too high in his arm action. I do like Grant's chances at cleaning up his delivery, however. He's very athletic, also playing third for Milford High, and pitchers with added athleticism often have an easier time making adjustments to their mechanics and repeating them over time.
I haven't heard much about his signability, but he's not committed to a top program--he's slated to attend Liberty--so that may indicate he's more signable than some.