Real short version: picked by Toronto out of Kentucky with the 37th overall pick (supplemental) in 09. Didn't come to terms. Ruled ineligible by the NCAA. Filed lawsuit, then dropped it. Signed with the independent American Association. Boras client. Due to rust or nagging injuries or both, didn't dazzle in the indy league. Due to Boras client-hood or nagging injuries or both, dropped to the 4th round, where the Ms took him.
Things to know: 6-4, 220 lefty. Started college at 6-2, 200 and got both taller and more bulked up while there. Had a 3.3 GPA with an accounting major. From British Columbia, as are Michael Saunders and Tyson Gillies (traded in the Lee acquisition). As Jay Y. ("JFrom") points out, the Ms know what they're doing with the Canadian kids.
Said to throw mid-90s and "touch 98" but didn't show that at Grand Prairie. Also, the curveball was considered above-average in college but didn't impress in the indy league. Change is considered average, and there is also a "power slider." Link to Keith Law report: http://www.baseballrumormill.com/2010/05/updated-scouting-reports-michael-choice-james-paxton/
However much stock one puts in Keith Law, note this: before his trip to Grand Prairie, Law had Paxton #12 overall talent in the entire draft. After the trip, he dropped him -- all the way down to #21. Lots of other folks had him pegged as first-round talent last year and this year (that is, excluding signability).
(A little additional explanation: his legal wrangling went through all of Jan. and Feb. He didn't sign with Grand Prairie until Mar. 31. So he was 6-8 weeks behind everyone else. His first 3 outings were pretty mediocre -- looks like Law scouted the very first one -- but his last start on May 30 was 5.1 IP, 2 H, 1 ER, 1 BB, 7 K.)
In the SEC in 09, he struggled with some gopheritis (including a 2.0 IP, 9 ER, 3 HR outing) and got dinged for a 5.86 ERA, but amazingly had more double-digit strikeout games (7) than single-digit ones (6). Finished with 115 K and 20 BB in 78.1 IP. Also, he was young for a college junior (20), and he's still only 21 now.
Bottom line: Paxton is the closest to the majors of any of the 2010 picks, and he may be the best talent. By picking him when he has no leverage (other than going back to indy league), he should be signable -- Boras notwithstanding. And getting him does not require trading Cliff Lee (only money).
And this: Churchill ranks him above Pineda -- http://prospectinsider.com/chat61210.php (see comment at 9:00). Then check out who he comps him to at 9:05. (http://www.baseball-reference.com/players/h/hamelco01.shtml)