The Cardinals were an exceptional team last season. They finished tied with their eventual World Series opponent Red Sox for the most wins in baseball (97). They were fifth in baseball with a 3.42 team ERA and third with a .332 on-base percentage. However, that excellence did not extend to their defense. Baseball Info Solutions estimates their fielders combined to cost the team 39 runs, which was second worst in the NL, ahead of only the Phillies.
If their start to the 2014 is any indication, the Cardinals have dramatically overcome that weakness. So far, Cardinals defenders have saved their team 40 runs. That’s a 79-run improvement over last year already and 10 runs more than the second best team, the Brewers. Using the 10 runs per win rule of thumb, that theoretically translates to a seven or eight win defensive improvement. If you prorate their Defensive Runs Saved total over a full season, the Cardinals are on pace to become the team with the biggest defensive turnaround from last season by a wide margin:
Several of the Cardinals' offseason moves have fueled their turnaround. Last season, David Freese cost them 14 runs at third base. They traded him to the Angels for noted gloveman Peter Bourjos, who has saved them four runs so far in center field. In addition, free agent signing Jhonny Peralta has saved nine runs defensively, and free agent signing Mark Ellis and call-up Kolten Wong have combined to save 11 runs at second base.
Of course, it is a lot to ask for the Cardinals to keep up this defensive pace. Should they falter, the Athletics, Mariners, Angels, and Rockies are the best candidates to potentially surpass them as the most improved defensive team.
Josh Donaldson (14 Defensive Runs Saved) and Josh Reddick (7 DRS) have been responsible for most of the Athletics’ defensive success. Meanwhile, the Mariners’ rebound is more about the "loss" of defensive liabilities like Raul Ibanez (-19 DRS) and Michael Morse (-16 DRS) than it is about excellent defense now.
Mike Trout’s own turnaround from a minus-9 DRS center fielder in 2013 to a plus-4 DRS center fielder this season has helped turn the Angels into the second best defensive team in the AL. J.B. Shuck and Collin Cowgill have also helped, the former saving six runs in left field and the latter saving five runs in right field. The Rockies have the best defensive infield in baseball. Troy Tulowitzki and Nolan Arenado have combined to save the team 21 runs on that left side alone. A commitment to defense has helped all five teams enter the thick of their respective division races.