These are the NL West's top middle-infield duos

All five middle infields in the National League West follow the same pattern: Each team boasts a franchise staple at shortstop, but each team has a bit less certainty at second base.

The question marks at second vary from team to team (and the rest of the offseason should provide a few answers). But there’s clearly no shortage of stars up the middle -- including Colorado’s Trevor Story, San Diego’s Fernando Tatis Jr. and Arizona’s Ketel Marte, to name a few.

So how do the NL West’s double-play duos stack up? Let's take a look:

The best

D-backs
In Nick Ahmed, Arizona has one of the game’s best defensive shortstops, as evidenced by his Major League leading 18 Defensive Runs Saved in 2019. He’s also an ironman, setting a club record with 1,381 innings last year. Meanwhile, the D-backs had hoped to sign a center fielder to allow Marte to entrench himself at second. But thus far they've come up empty. Marte posted a .981 OPS and 6.9 Wins Above Replacement, per Baseball Reference -- the highest among NL middle infielders. If he must play center, Eduardo Escobar could fill the second-base role (sparking a tight race between the Rockies, Dodgers and D-backs for top spot). Ildemaro Vargas remains a valuable utility man for Arizona, and Josh Rojas and Andy Young give the D-backs some depth options from the Minors.

The rest (alphabetically by team)

Dodgers

Although the Dodgers have pursued shortstop Francisco Lindor (among other upgrades), plenty of teams would love to have their middle-infield options. Corey Seager is the anchor at shortstop, coming off his third season with 4-plus WAR. At second, Gavin Lux is MLB Pipeline’s No. 2 overall prospect, and he’s already a Rookie of the Year favorite. Max Muncy, with back-to-back 35-homer seasons, often slides to second, too. The bench includes veterans Kiké Hernández and Chris Taylor, both postseason heroes, while Minor Leaguer Zach McKinstry will fight for a job.

Giants
Although Brandon Crawford is poised to return as the starting shortstop, his hold on the position appears more tenuous than previous seasons given his poor offensive production last year. Crawford, who turns 33 later this month, posted a .654 OPS in 2019 -- the fourth-lowest mark among qualified Major League hitters -- and might not be given as much leash under new manager Gabe Kapler. Mauricio Dubón, the Giants’ prized Trade Deadline acquisition last season, will enter Spring Training as the favorite to win the starting job at second base, but he could also see time at other spots, including shortstop and center field. Veteran Donovan Solano emerged as a valuable backup option in 2019, though the Giants will also use Spring Training to evaluate Kean Wong, who was claimed off waivers from the Angels in November.

Padres
The Padres spent the last decade searching for their shortstop of the future, and in 2019 they found him. Tatis is one of the sport's most exciting young players, and he will anchor short in San Diego. But after trading Luis Urías to Milwaukee, the Padres have serious question marks regarding Tatis' potential double-play partner. Jurickson Profar leads a long list of candidates for the second-base job -- a list that also includes Greg Garcia and Ty France alongside prospects Owen Miller, Jake Cronenworth and Esteban Quiroz. At the lower levels, the Padres boast a group of quality middle-infield prospects headlined by 2019 first-round pick C.J. Abrams, who burst onto the scene in his pro debut last season.

Rockies
This is an encouraging twosome, with Story, 27, squarely in the argument for best two-way shortstop in the game and Ryan McMahon, 25, showing signs of impact at second base. Story is the first shortstop in Major League history to begin his career with four straight seasons of 20 or more homers, and the second (joining Alex Rodriguez) with at least two 20-homer/30-steal seasons. He also had the fifth-most Outs Above Average of any MLB infielder, per Statcast. Last year, his first full Major League season, McMahon finished with 24 home runs and a solid .779 OPS. He showed growth at second base, after spending much of his pro career as a corner infielder. Behind Story and McMahon are two right-handed hitting options -- Garrett Hampson, who plays both positions, and top prospect Brendan Rodgers, who tried to play through a sore right shoulder and ultimately underwent surgery.