The 720 runs scored by Arizona, 17 behind Colorado, and about in line with their offense in general - the D-backs were third in batting average and second in OBP and SLG, with a triple-slash line of .264/.324/.414. They had the youngest offense in the league too, at 26.6 years old, and the majority of the players from 2015 will be back this year - and still on the right side of the aging curve, so there remains room for improvement through age. The main changes are in the middle-infield, where Jean Segura was swapped for Aaron Hill, and in right field, where Ender Inciarte was part of the package sent to Atlanta to bolster the rotation with Shelby Miller.
Catcher: Welington Castillo
"Beef", as he has become known, arrived from Seattle last June as part of the return for Mark Trumbo, and turned the position around the rest of the way, at least on offense. Arizona ended the year with more home-runs from the catcher's spot than any NL team, something no-one would have predicted when they went into the year with Tuffy Gosewisch and Gerald Laird there. Castillo has been raking in spring, but we all know how meaningful that is. He'll hit for power, certainly; the main question-mark is his defense - he has consistently rated poorly, for example, at framing. With Arizona's pitching key this year, handling them will become equally important.
First base: Paul Goldschmidt
MVP runner-up and starting 1B in the All-Star Game, Goldschmidt can no longer be considered under-rated. But he still, somehow, seems to find a way to surpass expectations, putting up arguably one of the best seasons in the league at the position since integration. The man is truly the complete package, even stealing 21 bases last year. Quiet, unassuming and undemonstrative, he is truly the anti-Harper, and whatever mistakes Kevin Towers made, the five-year $32 million deal Paul signed is among the best value in baseball. Health permitting, there is absolutely no reason why 2016 won't provide another All-Star appearance and MVP candidacy for Goldy's future.
Second base: Jean Segura
The team is hoping Segura, who may also see time at SS, can capture the form which took him to the All-Star Game in 2013, for over the past two seasons, Segura has an OPS+ of 69. The change of scenery may help, and distance from the tragic loss of Segura's infant son in July 2014 can be no bad thing either. Arizona could certainly use some improvement here, as this position was an offense black-hole last year; the OPS of .605 from it was the worst in the NL, neither Hill nor Chris Owings hitting worth a damn. That's a low bar to beat, and improvement here would help the D-backs offset possible regression at other places on the diamond.
Shortstop: Nick Ahmed
A 70 OPS+ would normally not be adequate, but Ahmed's fielding was so good he still managed to be worth 2.5 bWAR. As we discussed, the metrics show Nick's 2015 was the best defensive season ever by an Arizona shortstop, and with Andrelton Simmons now out of the league with the Angels, Ahmed should be in the running for a 2016 Gold Glove. That said, there is obvious room for him to get better at the plate, with a woeful .275 on-base percentage. The rumors linking him to St. Louis do not, as yet, appear to have any basis in fact, and I strongly suspect he's more valuable to the Diamondbacks than the Cardinals would be prepared to pay.
Third base: Jake Lamb
A decent rookie campaign for Lamb, despite missing 42 games with a foot injury. While he never quite recaptured his early-season form, the everyday job is his to lose at this point. He gave the team more quality defense at the hot corner, but Chip Hale seemed curiously reluctant to let Lamb face left-handed pitching. Jake made only four starts against an opposing south-paw, despite minor-league splits which looked entirely serviceable. Even if that continues in 2016, he'll still get the lion's share of playing time. I'd be nice if his power returned to the levels shown in the minor-leagues, as you want more than the six homers Lamb hit in 2015, out of your third baseman.
Left field: Yasmany Tomas
If there's one player key to the team's offensive success, it's probably Tomas. For he will, effectively, be replacing Ender Inciarte in the Arizona outfield, and in 2015, Inciarte was worth 5.3 bWAR, while Tomas was worth -1.3 bWAR. The importance of Tomas sorting it out, thus doesn't need much more emphasis. Last season saw Tomas tried (and failing) at third-base, and the far longer major-league season also seemed to take its toll. But Yasmany showed up to camp this spring looking leaner,. and hopefully can deliver something like the team's highest-paid position player for 2016 should. If he doesn't, Arizona's road to the post-season becomes a great deal tougher.
Center field: A.J. Pollock
You might be surprised how little Pollock was behind Goldschmidt in 2015 production: 1.4 bWAR and only 0.8 fWAR. For even though he made the All-Star Game, there's still an argument he's under-rated; by fWAR, he ranked 4th in the league, yet came only 14th in MVP balloting. I'd say hitting .315 with 20 homers, stealing 39 bases and playing Gold Glove defense deserved a higher position. A.J. has been struggling with elbow soreness this spring, and won't be back in game action until later this week, best-case scenario. If he isn't ready for Opening Day, that will certainly be a blow to the Diamondbacks,
Right field: David Peralta
The best failed pitcher ever to play the outfield at Chase, Peralta's remarkable career resurrection, from indy ball to the majors, is an incredible story, which won him the Unsung Hero title in our 2015 awards. This year, Peralta is being shifted from left to right field for defensive purposes, and will probably get to bat clean-up behind Goldschmidt. No pressure, David. He has had his issues against left-handed pitching; while the gap narrowed somewhat last season, it was still a very significant one, and if Peralta can figure them out better, he has serious potential to become a highly dangerous threat at the heart of the Diamondbacks' order.
If not hampered by injury, there's not much reason to think this offense will be any less good than last year: save Inciarte, the most productive members are all back, and there's scope for improvement at several spots. However, there are still some questions remaining. Can Segura and Tomas rebound? Will Castillo sustain his strong 2015? Is Lamb going to see, never mind handle, left-handers? But if this spring is any guide, the team averaging seven runs per game - admittedly, that's a cactus-sized "if" - then Arizona will be a formidable opponent, even on the days when its pitching staff gives up a few runs.