What does the future hold for the Red Sox at third base?

With the Yankees swooping in on Todd Frazier, the Red Sox looked stuck at the beginning of the week, having to promote from within to fill the void that had characterized third base at Fenway all year. With his sterling minor-league track record this year, it looked like Rafael Devers would be their man. And while the Red Sox acquired Eduardo Nunez earlier this week, Devers is still the key to the future at a position the Red Sox have struggled to fill for some time.

Through Tuesday’s games, Boston third basemen have posted an AL-worst -0.8 fWAR. (That is, in fact, a negative sign, and not a typo.) The only team with less value coming out of the hot corner are the rebuilding Phillies. 2016 wasn’t much better, as Boston 3Bs totaled 0.8 fWAR, tied with Oakland for dead last in the Majors. 2015 was even worse, when Pablo Sandoval and Deven Marrero cost the Red Sox several victories, posting -2.5 wins below replacement. Boston third basemen have not been in the top ten (or indeed, higher than 18th) since Kevin Youkilis’s 2011 season.

Enter the enormous potential of Rafael Devers, available to step into a newly vacant black hole.

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Coming into the year Andrew Benintendi topped Baseball America’s Top 100 prospects list, with Red Sox number two prospect Rafael Devers at 18th. Benintendi, while still progressing, has been quite good for Boston at the major-league level in 2017, while Devers worked his way up to number six on this month’s mid-season list. Showing great tools through the minor leagues, Boston has felt they have a good long-term plan for third base. That doesn’t mean they anticipated needing the 20-year-old Devers this season, but that’s baseball, Suzyn.

Devers got the call up to the “the show” earlier this week, after Boston parted ways with Pablo Sandoval (and nearly $100 million). Devers had already showcased an excellent 77-game stint at Double-A, and a bit more than a week's’ worth of knocking the cover off the ball in Triple-A. He displayed an excellent hit tool and power, and an ability to hold his own at third base with surprisingly agile footwork.

Backed by strong wrists and excellent bat speed and control, Devers did not disappoint in the minors. Through half a season in Double-A Portland, Devers showed a good hit tool, batting .300, and demonstrated his prodigious power. Over those 77 games, Devers hit 18 home runs and posted a wRC+ of 154.

Devers has the strength to hit to power to all fields, while keeping a well above-average batting average. Though he does not have the athletic speed of some prospects with his six-foot, 215-pound stature, he does have the arm strength to play a decent, if not perfect, third base.

Devers’ short stint in the majors so far has been a fun ride so far. His first big league hit was a home run off Mariners’ starter Andrew Moore, which seemed like a good omen for his future at the hot corner. But baseball is never as simple as they seem, and the Red Sox traded for decent-bat, atrocious-defense infield utility player Eduardo Nunez. (My SB Nation colleague Grant Brisbee broke down the pieces Boston sent to the Bay for Nunez.)

The question from here forward is how do Devers and Nunez fit into a playoff-contending Red Sox team? As the Yankees remain on the Sox’ heels, with the Rays right behind them, who is the better play for the remaining ⅓ of the season?

Devers brings with him high risk and likely moderate reward. At his best, he can be a .300 hitter with plus power, who has the potential to post 10+ home runs the rest of the way. With limited scouting reports on his MLB ability, there’s the possibility he tears through the league for the next eight weeks.

There’s also the chance he struggles against big-time pitching; after all, he’s not even 21 years old yet. The last thing the Red Sox want to do is force a prospect to develop in the Boston pressure-cooker that is a late-summer pennant race.

But Nunez isn’t a high-upside play either. He’s pretty much a known commodity at this point in his career, in his age-30 season and not getting any better in any aspect of his game. The righthanded hitter is probably good for a .290-.300 batting average... and not much else. With a career 5.1 percent walk rate, and very limited power, the possibility of greatness is simply not there. There’s no chance Nunez blasts double-digit home runs over the next 60 games. He’ll certainly provide frustratingly terrible defense, and he’s likely to hit at a level Devers is capable of as well. The chance of him looking totally exposed, however, is less than it is with the unproven 20-year-old.

The worst scenario here is the Red Sox keeping Devers at the major league level, while playing Nunez most of the time. Not getting their future third baseman at-bats in order to play a not-very-good rental is less than ideal. Having traded some longer-term assets for Nunez, it’s likely he sees the bulk of the time at third base, which should mean that Devers is headed back to Triple-A. Replacing a shiny prospect with an average-hitter (101 wRC+ this season) who plays bad defense is a curious choice in a pennant race, and might indicate some skepticism on the part of the Red Sox when it comes to Devers’s hot summer. It looks like we’ll likely have to wait until 2018 to see the ultra-prospect everyday.