When I look at the Yankees' roster for 2018, the first thought that comes to mind is “HOT DANG, GIANCARLO STANTON IS A YANKEE.” The second thought is “man, that's a lot of outfielders for one available spot.” With Stanton and Aaron Judge (a.k.a Thunderous Beef-Men #1 and #2) manning the corners, center field is the only open position for the four remaining candidates, namely Aaron Hicks, Brett Gardner, Jacoby Ellsbury, and Clint Frazier. I'll take “What is a logjam?” for $500, Alex.
Of course, it's not a given that the Yankees will roll into camp next spring with six outfielders on the 25-man. Clint Frazier has already been mentioned in trade talks, and if the Yankees do manage to pry Gerrit Cole away from the Pirates, he's probably going to be included in Pittsburgh's return. However, it's hard to see any of Hicks, Gardner, and Ellsbury being dealt this offseason, given Brian Cashman's confidence in Hicks, Gardner's age, and Ellsbury's sunken contract (although San Francisco might have something to say about that last one). Thus, there's a real possibility that the Yankees will carry three backup outfielders on the 2018 team. That wouldn’t be so bad.
Why is having an outfield logjam a good thing? Well, firstly, it allows the Yankees to see if Aaron Hicks is a legitimate starting center fielder without forcing them to ride or die with him. I share Cashman's faith in Hicks, and I think he has a higher floor than everyone gives him credit for. He has well above-average plate discipline, and while he was hitting over his head in the first half last season, his contact quality suggests that he hit the ball like a true-talent league-average hitter throughout the year, even during his second half slump. Pair that with his defense, which was never a question to begin with, and you have yourself a 3-4 win player, even if you think much of Hicks' power surge wasn't real. I think it's safe to say that he's a better option in CF than any of Gardner, Ellsbury, or Frazier.
However, Hicks obviously comes with a lot of question marks. Excluding 2017, he has never once crossed the 100 wRC+ threshold, and there's no guarantee that he won't lose his 2017 offensive mojo and revert back to his 2016 ways next year. Including 2017, he has never once reached 400 plate appearances in a single season. This is all scary stuff for a team that's trying to win it all next year.
With the Yankees' current outfield situation, they don't have to hitch all of their hopes onto Hick's back; they can run him out there and hope for the best, while having entirely competent options if he fails to perform. Ellsbury and Gardner both have experience in CF, and while they've both lost a step in the field, they can still hold the fort down in a pinch. Ellsbury in particular gets a lot of flak for his albatross of a contract, but as a player he's far from useless; he has been pretty reliably worth 1-2 wins every year since 2015, which is way more consistent than Hicks has been. Thus, having Ellsbury and Gardner enables the Yankees to explore Hicks' upside without having to pay for his downside, which is an enviable position for a contender to be in.
Plus, as a general point, having outfield depth is crucial in keeping players healthy. Aaron Judge and Giancarlo Stanton are both a) huge, and b) (hopefully) going to be in the Bronx for a long time, so it's in the Yankees' best interests to keep their knees intact. Scheduling regular DH days for them, with Hicks/Ellsbury/Gardner/Frazier filling in, would go a long way towards achieving that goal while ensuring the quality of the on-field product. The Yankees may even get something more out of a healthy Ellsbury in a reduced role, given that he has been pretty good in the few stretches of time when he was fully functional.
So, the Yankees' outfield logjam allows them to take a risk-free chance on Hicks, and it also allows them to try to maintain Judge and Stanton's long-term health and productivity. The tricky part lies in getting Frazier regular at-bats, but having the DH spot available should give the Yankees some leeway to squeeze him in. As problems go, having too many outfielders doesn't seem like such a bad one to have.