The D-backs and Rockies have had exceeded the expectations of many preseason prognosticators, and while those two teams would meet in the National League Wild Card Game if the season ended today, a source said the two clubs are actively seeking a corner outfield bat to bolster their respective lineups.
The Cubs and Braves are creeping up in the standings; Chicago entered the week 5 1/2 games behind the Rockies for the second Wild Card spot, while Atlanta was only six games back.
So while they're competing for the two Wild Card spots on the field, it appears Colorado and Arizona will be battling each other on the outfield market over the next two weeks, too.
The source said both clubs are looking for "solid everyday bats" and not superstars, though the coveted bat for each could be J.D. Martinez of the Tigers, who would be a big boost to either team in the lefty-heavy NL West. Martinez has only 36 at-bats against lefties this season, though he's sporting an eye-popping 1.738 OPS with six homers in that small sample. His career OPS against southpaws is a healthy .903.
Andrew McCutchen of the Pirates could also be a fit, as his 1.194 OPS against lefties is tops among all outfielders with at least 75 plate appearances. Unlike Martinez, who is a free agent after this season, McCutchen has a relatively modest team option of $14.5 million for 2018, so he wouldn't be a pure rental.

If they're unable to land either Martinez or McCutchen, then switch-hitting Melky Cabrera of the White Sox (.787 OPS vs. left-handers this season) could be a viable fallback plan. Cabrera is eligible for free agency this offseason, along with Jay Bruce and Curtis Granderson of the Mets, two left-handed-hitting outfielders who could be available.
Although the Rockies welcomed Ian Desmond back from the disabled list this weekend, Carlos Gonzalez is in the midst of a rough season. The 31-year-old is hitting .214/.293/.328 with six homers in 77 games.
According to a second source, the Rockies' Minor League system "is so stacked" that Colorado ought to be able to outbid the D-backs for just about anybody.
Arizona has A.J. Pollock and David Peralta locked into two of its outfield spots, but Yasmany Tomas has been injured and inconsistent, leaving left-field duties to Daniel Descalso and Chris Herrmann.
Yonder staying put?
Yonder Alonso's value may never be higher than it is now, having coming off an All-Star first half that had him entering the week with 21 home runs and a .924 OPS. He's slated to become a free agent at the end of the season, leading to natural speculation that the Athletics will move him before the July 31 non-waiver Trade Deadline.

But a source with knowledge of the situation believes that Oakland will "take a shot" to re-sign Alonso between now and the Deadline, hoping to lock him up to a long-term deal. Even if that happens, it's far from certain that Alonso would ink a new deal with only two-plus months left in the season.
If Billy Beane and the A's decide to deal Alonso, they might encounter another problem: the first-base market.
"It's only one team," a source said. "Unless somebody goes down, the Yankees are the only team that needs him."
The Red Sox, who are also trying to fill their void at third base, could also be in the mix. Mitch Moreland has fallen into an untimely slump, hitting .169 with a .528 OPS since June 15.
They're not available ... unless they are
The Marlins have indicated that they aren't trying to sell any of their young, controllable stars, but that doesn't mean they aren't looking around just in case an offer too good to refuse comes their way.
With that in mind, a source told MLB.com that a top baseball operations executive was in Arkansas last week to get a first-hand look at right-hander Dakota Hudson, the Cardinals' first-round pick in the 2016 Draft. Despite throwing only 13 1/3 innings in Rookie ball and Class A last year following the Draft, the 22-year-old Hudson was sent to Double-A Springfield to start '17. He has looked good, posting a 2.77 ERA with 69 strikeouts, 30 walks, and just five homers allowed in 100 2/3 innings.
The Cards are looking for outfield help, so it's possible they're trying to put together a package to land either Christian Yelich or Marcell Ozuna. Yelich is signed for $43.25 million over the next four years, while Ozuna has two years of arbitration eligibility remaining beyond 2017.

This and that
• One industry source believes the Cubs will be the team to trade for Orioles closer Zach Britton.
"If you have a chance to add Britton to your club, you do it," the source said. "Theo [Epstein] has the Minor Leaguers to get it done."
• According to an American League executive, the Yankees were "in strong" on Jose Quintana before the Cubs landed the lefty from the White Sox.
"They were quietly deep in it," the executive said.
• Brad Ziegler is being shopped around by the Marlins, who, according to a source, are willing to eat a substantial amount of money on the right-handed reliever's contract. Ziegler is owed a little more than $3 million for the rest of this season, and he will earn $9 million in 2018.