As the A's have gone from AL West front-runners to a second-place team trying to keep up with the Los Angeles Angels, much of the blame for their recent struggles is traced back to the deadline day trade that sent their star outfielder nERD of 0.80 means a lineup full of Dunns would score 0.8 runs a game more than a league-average player, better than Cespedes' nERD of 0.74.

Still, it's hard to ignore that difference in fWAR, 3.2-to-0.1 in favor of the young Cuban.

And when compared to John Jaso, who has been Oakland's primary designated hitter, Dunn's numbers aren't all that much better. He's hit many more homers than Jaso (20-to-9), but also has 91 more plate appearances. Jaso's on-base percentage, and wRC+ are both better than Dunn's, while Dunn has more raw power (ISO) and a better wOBA than Jaso.

The A's hit just 22 home runs in August, tied for sixth-best in the American League, and have the fourth-most homers of any AL team this year. They're hoping the addition of Dunn, who is looking to make his first postseason after 1,975 games, will give them some much-needed thump in the middle of the lineup.

But when you break down the numbers, it's not clear how much they gain over Jaso, other than home runs. Both players perform well against right-handed pitching (Dunn's .808 OPS is slightly better than Jaso's .793), and both are equally poor against left-handers (Dunn's OPS of .563 is better than Jaso's .468), so there's no obvious advantage in lefty-righty splits.

Dunn can draw a walk and hit home runs, but he doesn't do much else. If the A's are going to break out of their offensive funk, Dunn can certainly play a role. But it'll be up to the rest of the lineup to snap out of the malaise they're in.

Dunn isn't going to be the savior.