Edwin Jackson used to be the #4 prospect in baseball.
Getting his first taste of the bigs in 2003 (as a 19-year old, no less), Jackson had a huge reputation to live up to early on in his career. For a long, long time, he never lived up to it.
This is an auspicious start to a career, to be sure. It's important to keep in mind a few things, though:
a) 24.2, 28.2, and 36.1 are essentially meaningless sample sizes.
b) The average 22-year old pitching prospect is getting ready to finish AA.
The thing that really pops out to me is the hellacious WHIP, here. You can't pitch in the bigs with a whip over 1.4; it just isn't going to happen.
Jackson would be traded as a 22-year old, a 24-year old, a 25-year old, a 26-year old, and as a 27-year old TWICE. That's insanity.
As Jackson aged, he looked more and more like a journeyman 5th starter. It wasn't until 2010 until he really started to break through; I'll show you why I think that is.
Jackson has 3 primary offerings. His main pitch is a 93-94 mph fastball that he throws 60% of the time. As you'd expect from a guy with a primary-pitch fastball, it hovers around -.6 runs per 100, which is obviously below average but relatively fine for a pitch you're throwing in the worst counts. Edwin also throws an 86 mph slidepiece (30%) that has consistently been a plus pitch over his career. After that, Jackson throws an awful changeup at 86 mph; he also throws maybe 2 curveballs a game.
Jackson's success of late has been almost entirely predicated on his ability to throw the first pitch for a strike. Until 2010, Jackson's average for F-Strike% was 54%; from 2010 onwards, it is 59%. You may think that's no huge difference; it is. The correlation between throwing your first pitch for a strike and throwing your last pitch for one is pretty high. Really, no peripheral of Jackson's has changed besides K/9 (a modest downturn in BB/9, also attributed to getting the first pitch over for a strike), as far a LD%, HR/FB%, LOB%, yet his performance has been a lot better.
I don't know enough about Jackson to hazard a guess as to why he's throwing more first pitch strikes, but whoever told him to should get a free meal from the Scott Boras.
Edwin signed a 4/52 contract with the Cubs. As dmick89 pointed out, the Cubs are paying right around the market price. It's important to realize that no every signing is going to be a steal. Teams with financial advantages need to use those advantages, and the Cubs just did. Even if the Cubs don't compete until 2015, they'll still need pitchers that season, and Jackson will be one (even if he's the #4 or #5 on a good team). He doesn't have a NTC, so we can get under the contract for prospects or relief if necessary, and he's as good a bet (for a pitcher) to earn his contract as anyone. Next year's FA class is dogshit, and they'll likely get worse. This is a good signing for a good pitcher.