NL Wild Card: Position-by-position breakdown

This year's National League Wild Card Game features two of baseball's best comeback stories, given the Rockies or D-backs hadn't posted a winning season in the previous five seasons. Now they're both in the playoffs, and they're set to face off for the 20th time this year, with aces Jon Gray and Zack Greinke on the mound. Arizona won 11 of the 19 regular-season meetings between the NL West rivals.
Those head-to-head victories helped give the D-backs home-field advantage in this game, and that's a pretty interesting subplot to keep an eye on, given how differently each of these teams play at home as opposed to being on the road, which is understandable since Chase Field and Coors Field are likely baseball's two most extreme home parks.
The winner gets to face another NL West rival in the Dodgers, but that's another problem for another time. First they have to get past one another. Who's got the edge? Let's break it down position by position. (Batting numbers are presented with traditional AVG/OBP/SLG and Weighted Runs Created Plus, or wRC+, a park- and league-adjusted number where 100 is set as "league average" for easy comparison.)
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Catcher
Colorado's catching responsibilities have gone from a collection of Tony Wolters, Ryan Hanigan and Dustin Garneau at the start of the season to summer trade acquisitionJonathan Lucroy, but the collective's park-adjusted line of .249/.342/.332 (61 wRC+) ranks just 29th of the 30 teams. Lucroy has done a fantastic job at getting on base with the Rockies (.429 OBP) but has hit just two homers in 46 games with Colorado. Chris Iannetta (.254/.354/.511, 120 wRC+) has been the best hitter of any catcher on either side, and Jeff Mathis returned from injury in time to be available to bring his elite framing skills back for Arizona, too.
Advantage: Tie

 First Base
There may not be a bigger gap at any position in this game than at first base, where Paul Goldschmidt (.297/.404/.563, 142 wRC+, 36 home runs) is wrapping up another dominant season, one that will garner him strong support for the NL Most Valuable Player Award. Meanwhile, Mark Reynolds had a huge first half (.284/.379/.513, 119 wRC+) but has expectedly come back to earth since, hitting .243/.314/.449 (82 wRC+) since the All-Star break. Ian Desmond, originally expected to play first, started 22 games there around multiple injuries and time in the outfield.
Big Advantage: D-backs

 Second Base
DJ LeMahieu (.310/.374/.409, 94 wRC+) wasn't quite able to match his breakout 2016 (.348/.416/.495, 130 wRC+), falling back towards his career averages, but he still offered league-average production with a solid glove, and with this matchup, we might be fortunate enough to see one of baseball's wildest shifts again. Brandon Drury's conversion from utility man to everyday second baseman went well enough, but his bat took a step back, as well (.267/.317/.447, 92 wRC+), giving LeMahieu the edge here.
Advantage: Rockies

Shortstop
We'll call this one a toss-up, with an asterisk. Trevor Story's sophomore season (.239/.308/.457, 81 wRC+) looked little like his smashing debut (.272/.341/.567, 122 wRC+), though reviews on his defense were strong and he hit for more power in the second half (.520) than the first (.396). On the other side, Arizona lost both Nick Ahmed and Chris Owings to broken hands, so they've been rolling with 23-year-old Ketel Marte, who spent most of the first half in the Minors. His overall production (.260/.345/.395, 89 wRC+) was similar to Story's, but he sustained a hamstring injury on Sunday, leaving his status uncertain. If he can't play, utility infielders Adam Rosales or Daniel Descalso probably would.
Advantage: Tie
 Third Base
It should be noted, first, that Jake Lamb is really, really good. Over the last two seasons, he's hit 59 homers with a .248/.345/.498 (112 wRC+) line, making him a worthy complement to Goldschmidt. But he remains extremely vulnerable to left-handed pitching (career .159/.265/.301, 47 wRC+), has faded for the second half for the second year in a row (.204/.332/.403, 87 wRC+) and, of course, most players pale in comparison to Nolan Arenado. Colorado's third baseman is going to get some strong MVP consideration, thanks to hitting .309/.373/.586 (129 wRC+) with 37 homers, and he leads the world in spectacular defensive plays.
Big advantage: Rockies

 Left Field
It's probably fair to say that neither team got what they wanted out of left field this year, as David Peralta followed up his spectacular 2015 (.312/.371/.522, 137 wRC+) with an injury-marred 2016 and a fine, but not great, 2017 (.293/.352/.444, 104 wRC+). The Rockies had hoped the highly-touted David Dahl would take the left-field job, but rib and back injuries cost him the entire season. Instead, Desmond (.274/.326/.375, 69 wRC+) underwhelmed when healthy, and Gerardo Parra's line was heavily boosted by his home field (.377 OBP at home, .302 on the road.) Peralta gains the edge, but it's a small one.
Small advantage: D-backs

 Center Field
This should be closer, because A.J. Pollock was blossoming into a star from 2013-15 (combined .297/.349/.468, 121 wRC+), but then lost 2016 to elbow surgery and had an only average 2017 (.266/.330/.471, 103 wRC+). Meanwhile, Charlie Blackmon has taken the opposite route, transforming himself from an average player in 2013-15 (combined .291/.340/.449, 102 wRC+) into a superstar over the last two seasons (.327/.390/.578, 137 wRC+), likely becoming a top-5 finisher in MVP balloting. It's worth noting his huge home/road splits, as he hits .391/.466/.773 at home against just .276/.337/.447 on the road, but he's not a mere Coors Field creation. He's a difference-maker.
Big advantage: Rockies
Video: LAD@COL: Blackmon makes history with 454-foot homer
 Right Field
Carlos González has had a ton of success with the Rockies, but 2017 (.262/.339/.423, 84 wRC+) was his second down year in the last four, and his tenure in Colorado may be nearing an end -- though it's worth noting that he finally got hot in September. That said, it's impossible to match up to the impact J.D. Martinez has had on the D-backs, since he hit an unbelievable .302/.366/.741 (172 wRC+) with 29 homers after arriving from Detroit and tied the National League record for most homers in September.
Advantage: D-backs

 Starting Pitchers
Greinke is going to get the ball for Arizona, and he's had a big rebound after a disappointing 2016 debut, upping his strikeout rate from 20 percent to 27 percent, cutting his ERA from 4.37 to 3.20 and allowing just two more homers in 44 more innings, likely on his way to a top-5 NL Cy Young finish. For Colorado, Gray is well on his way towards being considered an ace, too, as he's allowed more than three runs only three times in 20 starts, and not once since July. Greinke's long track record earns him the edge here, but Colorado benefits from this being a one-game series, as Arizona's big advantage in rotation depth is somewhat muted in a single game.
Advantage: D-backs

 Relief Pitchers
By some measures, the 2017 Rockies bullpen is the best in team history, and while it's fair to note Colorado has often had trouble putting together a solid relief unit, this is a legitimately good and deep group, led not only by closer Greg Holland, but also Jake McGee, Chris Rusin and Pat Neshek. The D-backs do have a breakout weapon in Archie Bradley (1.73 ERA), and rookie Jimmy Sherfy is intriguing, as he's been unscored upon in his first 10 2/3 Major League innings, so manager Torey Lovullo has options of his own. But if the D-backs get a lead, the question is which version of Fernando Rodney they get. In 54 of his 61 appearances, he's allowed zero or one runs; in his seven "bad" games, he's allowed 22 runs in just four innings.
Advantage: Rockies