Opinions vary. Pat Lackey comments
In contrast, WTM suggested that despite his underwhelming performance in Pittsburgh thus far, Locke is
a good prospect who should get serious consideration for the Pirates' 2013 rotation.
In his IL Top Prospects column, John Manuel ranked Locke number nine (having noted his reservations about players not in the top three) and wrote
Because he lacks a plus pitch, Locke profiles as a No. 4 starter. He evokes Ted Lilly with a slight hip turn and pause in his delivery, which gives him some deception. He does little things well, such as holding runners and fielding his position.
And regarding McPherson Lackey tweeted
You can lump him in with Locke and Wilson. Maybe helpful, not someone I'd be relying on.
Carson Cistulli, in writing about The Next Michael Pineda, notes that big strong pitchers with good fastballs who don't walk batters are often quite successful. McPherson is 6'4" and 220. His fastball sits around 93 mph and he walked only nine batters in 67 innings in AA and AAA in 2012 (versus seven in 24 major league innings).
Jeff Locke doesn't throw as hard (about 90 or 91), walks more batters (7.4% per plate appearance in AAA versus 5.8% for McPherson), and strikes out fewer (22.4% per plate appearance in AAA versus 24.6% for McPherson). The differences are pretty small, but small differences can be what separate an AAAA player from a reasonably successful major league player.
Obviously the Pirates need more pitching even if Cole is lights out. In these two players do we have two candidates for a good major league rotation, one, none? I'm not sure.