The starting rotation was supposed to be a strength for the Braves, but they instead opened today with just one qualified starter with a sub-4.40 ERA. Ben Sheets has provided a lift two starts into his comeback and Tim Hudson has been his typically reliable self, but Mike Minor, Randall Delgado, and Jair Jurrjens have struggled to varying degrees while Brandon Beachy blew out his elbow. Atlanta remains right in the thick of the playoff hunt despite ranking middle of the pack in rotation ERA and FIP (both 4.04).

In an effort to shore up the staff, the Braves acquired Ryan Dempster from the Cubs this afternoon. It’s unclear what they gave up as of this writing, though Delgado has been rumored. Dave O’Brien, Jon Heyman, and Mark Bowman all deserve some credit in breaking the news. The veteran right-hander has ten-and-five no-trade protected but waived it to join Atlanta. He reportedly did not demand any kind of extension or other compensation to approve the trade, so he gets brownie points for that.

Dempster, 35, recently missed some time with a lat strain but otherwise is in the middle of his best season as a full-time starter. His 2.11 ERA is backed by an sky-high 83.9% strand rate, something that may be more sustainable than you think. Dempster’s become more of a fly ball pitcher at this point of his career (42.2% grounders this year) and Atlanta has a big home ballpark with a dynamite defensive outfield led by Michael Bourn in center. Maybe 83.9% won’t last forever, but a regression to the 72.6% league average is not a foregone conclusion.

Those fly balls and outfield defense should also go a long way towards keeping Dempster’s BABIP down. He’s working on a career-low .245 mark right now (.301 career) and while that probably won’t last all season, regressing all the way back to the .293 league average is again no sure thing. It’s tough to overstate how favorable the switch is for Dempster — he’s going from a hitter friendly park where Alfonso Soriano and Bryan LaHair roam the corners to a pitcher’s park with three good-to-great defensive outfielders.

There are still some concerns of course. Dempster’s career-low strikeout rate (7.07 K/9 and 19.5 K%) has been trending in the wrong direction basically since April…

His swinging strike rate (9.3%) is identical to last year and in line with 2010, so he’s still missing bats. It’s worth noting that based on the PITCHf/x data, Dempster is throwing considerably more sliders and splitters this year than the last few seasons. Matt Garza showed a similar adjustment following the trade to Chicago last year, so maybe it’s a pitching coach thing. Either way, the drastic decline in strikeouts — he was over 8.5 K/9 and 21.5 K% in each of the last two seasons — is a red flag.

We don’t know what the Braves are sending the Cubs just yet, but acquiring Dempster drastically improves Atlanta’s chances of winning this season assuming prospects and not big league pieces went the other way. They got a reliable innings eater who, even if his performance down the stretch isn’t as impressive as the first half, will be an upgrade over three current starters. It could be as much as a three-win improvement, though two seems more likely. Dempster gets to join a contender and stay in the National League, the best case scenario for a veteran who (probably) wants to win and land a nice multi-year deal this winter.

* Sorry, couldn’t pass up the obvious headline pun.