Mike Leake's five-year, $80 million deal (plus an option year and a full no-trade clause) is about the going rate for a league-average starter right now, but Leake's history of putting up innings and getting ground balls made him the ideal fit for the St. Louis Cardinals, who also benefit by keeping their first-round draft pick on top of the two supplemental-round picks they'll get for losing Jason Heyward and John Lackey.
Leake has been extremely durable and consistent over his major league career, making over 30 starts in each of the last four seasons and throwing more than 1,000 innings for the Cincinnati Reds before the mid-2015 trade to San Francisco. He's never suffered an arm injury, even though he was worked fairly hard as a rookie by then-manager Dusty Baker, and his performance has gradually improved with experience; his three best seasons by ERA and FIP were his past three, 2013-15, and those would likely have been his top three seasons by Baseball-Reference's WAR had he not missed three starts with a hamstring injury after he was traded.
What Leake promises to provide the Cardinals is twofold: bulk innings and ground balls. The first is something the Cards need badly, the second is something they value highly.
The Cardinals' rotation was short of innings before this signing, and Leake should provide them with 190-200. Lance Lynn is out for the year; Carlos Martinez ended the year on the shelf with a shoulder issue; Jaime Garcia and Adam Wainwright missed big chunks of 2015, although Wainwright's injury wasn't to his arm; and Michael Wacha just reached 150 innings for the first time, one year after missing about a third of the season with arm problems. They needed something akin to certainty, and Leake is about as certain as a pitcher can get -- which is also why five years, which seems crazy for some pitchers, seems perfectly reasonable for him.
The Cardinals have long preached the value of ground balls to their pitchers, with Garcia, Martinez and Wainwright all above 50 percent in 2015, each of whom having done so at least once before in their careers. Leake has a career 50.2 percent groundball rate, and has benefited from having an excellent defense behind him in Cincinnati, particularly Zack Cozart at shortstop. His BABIPs will likely take a hit while he's playing in front of Jhonny Peralta, Matt Carpenter, and sometimes Jedd Gyorko, but the groundball tendency has also kept Leake's home run rate down even though he pitched half his games for the Reds in a good home run park. It seems likely that the loss of the defensive boost and the escape from Great American Ballpark will more or less cancel each other out.
There's more to Leake's value than just his arm, however. A two-way player at Arizona State, Leake remains a very good hitter for a pitcher, with a career .212/.235/.310 line and six homers in 375 non-bunt plate appearances. (NL pitchers as a whole hit .133/.160/.171 in 2015.) He's also an outstanding fielder, as you might expect from a highly athletic guy who played both ways in college and can still swing the bat, adding a couple more runs of value every year.
The signing should fill the Cardinals' external rotation needs, with Marco Gonzales the best option for the sixth spot and Tyler Lyons and Tim Cooney around as emergency starters. They could use a true center fielder, but otherwise the lineup and rotation seem set for the start of the season, allowing general manager John Mozeliak to focus on minor upgrades like the deal where he acquired Gyorko as a platoon bat and utility infielder.
The signing leaves Scott Kazmir and Wei-Yin Chen as the two best starting pitchers still available as free agents, with Mat Latos, a huge dropoff in durability and makeup from Leake, as the best right-handed starter option on the market. Kazmir, in particular, should be able to cash in on this deal -- albeit for a shorter duration -- as he offers better output on a per-inning or per-start basis than Leake but without the promise of consistent innings.