What went right
Rookie Wade Miley has been a pleasant surprise in the rotation, Paul Goldschmidt has proven to be a decent power threat, Jason Kubel had a great power season and Miguel Montero once again had a good year at the plate. And how about Aaron Hill? There aren't many better offensive second basemen in baseball. As a whole, when healthy, this is a good defensive team, too.
What went wrong
I'll start with just two words: Justin Upton. It wasn't just him, though. Ian Kennedy took a huge step back from last season, Trevor Cahill proved a mediocre rotation addition (in fact, they'd surely rather have Jarrod Parker back) and Ryan Roberts was awful before being traded. Promising young starting pitchers Trevor Bauer and Tyler Skaggs both showed they weren't quite ready this time around. Of course, there were also the injuries. Chris Young couldn't stay healthy enough to reach 100 games played and Daniel Hudson had to undergo Tommy John surgery after making only nine starts.
MVP: The Astros. Arizona roughed up Houston six times in six games, outscoring the Astros 56-19.
LVP: According to Baseball-Reference.com's WAR, Justin Upton has been just about four wins less valuable this season than he was last season. Again, he wasn't the only reason the D-Backs disappointed, but take four losses and make them wins and they are right in the thick of the wild-card race. He's the easy pick.
Free agents to be: RP J.J. Putz ($6.5 million club option), RP Matt Lindstrom ($4 million club option), RP Takashi Saito, C Henry Blanco ($1.24 million mutual option)
Gameplan heading into the offseason
Don't expect the Diamondbacks to be overly active, as they have a solid, young nucleus already in place and can expect improvement from Kennedy, Upton, Bauer and Skaggs. Knowing general manager Kevin Towers and his affinity for bolstering the bullpen every chance he gets, I do expect him to be active on that front.
Otherwise, though, the D-Backs figure to be one of the more quiet teams this offseason. At this point, they are 15-26 in one-run games and figures like those generally turn on little more than luck. Knowing this and expecting improvement and better health, the best guess is we'll only see minor tinkering from Towers and company.
Ridiculously premature prediction for 2013
In a tough division, the D-Backs again hover around .500 for most of the season and have to fight the urge to deal Upton.