Everyone wanted Ryan Roberts to succeed. He seemed like a fun loving guy, had that journeyman makes good backstory, the tattoos and grand slams and good fan reputation. Roberts personified the 2011 team more than perhaps anyone else, and it's probably fitting that his regression was a harbinger of the regression the rest of the team faced. It's not his fault, of course. He just wasn't going to suddenly wake up at 30 and be a better player. We got one fluke year out of him, but we were greedy to hope for more.
His slip backwards wasn't necessarily anything more than a loss of power, and an inability to take walks. His slugging went from .427 to .360, and his OBP went from .341 to .296. His strikeout rate went up by 1%, while his walk rate went down by almost 3%.
I could quote a variety of numbers to show his decline, but I imagine one with eyes saw it. If he had any saving grace this year it was his defense, which actually saved him from having negative bWAR. fWAR pegged him as a better player, giving him 1.3, but it doesn't completely pass the smell test to me when he had a wRC+ of 77. Remember, wRC+ is designed to generally have 100 be average in creating runs. He was well be low average in this, and he didn't contribute much to the D-backs for the 2012 season.
Eventually he was shipped off to Tampa Bay, and Chris Johnson was acquired from the Astros. Johnson certainly fared better, but he was incredibly streaky. He had a hot start after being acquired, and then cooled off. For the season, however, his OPS+ was 115 for the D-backs, which is pretty good. fWAR rated him about as equal as Roberts, but wRC+ was another prime difference. Fangraphs had him at 108, putting just above average.
Where Johnson likely faltered was on defense. The hot corner isn't called the hot corner for nothing, and it's a position that requires great reflexes and a great arm. I'm not going to make a claim on his arm strength, but he's not very good defensively at third. His UZR/150 suggests he would cost a team 10 runs over 150 games by his 2012 numbers, while Roberts would save a team 4 runs.
Johnson reminds me a bit of a certain other D-backs third baseman who could hit, sometimes, but was a statue on defense: Mark Reynolds. Johnson doesn't have his power, but he's a similar high strikeout guy (25% of the time in 2012). It's certainly a concern moving forward, which is why Johnson probably won't be a long term solution unless he improves.
That potential, or even potential for potential, is what separates Chris Johnson from Ryan Roberts. The former is still relatively young at 28 and only only 4 seasons of major league experience. Roberts, on the other hand, is 32. It's much easier to believe that a younger player (though Johnson really isn't that young anymore) will still be able to improve. But we should have been wary that a career utility guy suddenly had a break out year at 30 in 2011. It shouldn't be surprising that third base in 2012 declined, even with a halfway decent effort from Johnson.
Overall, I'll have to rate this at a solid D.
Jim. This was likely close to the position of biggest concern going in to the year - that and SS - and unlike SS, there wasn’t much overachievement going in. Right from the get-go, Ryan Roberts regressed from the career year he had posted in 2011, and it largely proved a revolving door of mediocrity thereafter. There was decent if unsustainable production from Cody Ransom for a few weeks, and Chris Johnson (on the road, at least) gave us some solid numbers at the end of the year. But a .240 average, playing half the time in Chase Field, is basically terrible, and will certainly need to be improved next year. Grade: D-