By position (the game isn't played this way but I don't care):
C
NY - Sanchez/Romine
Bos - Leon/Vazquez/Swihart
Edge - NY
Leon is solid defensively, as is Vazquez. Swihart is a nice athletic versatile piece. But for all his problems (and they are real), Sanchez is the single biggest difference-maker of this group of five players. By a mile. His power alone can swing games.
1b
NY - Voit
Bos - Pearce/Moreland
Edge - NY
I hate to say it but Voit is an animal right now. His line since coming to NY: .333/.405/.689/1.095 with 14 homers in just 148 ab. Pearce and Moreland are just fine, but Voit has been a game-changer.
2b
NY - Torres
Bos - Kinsler
Edge - NY
Kinsler is a pro. Torres is a dynamic young player with a lot of power. One of the best young players in baseball. This one isn't particularly close, though Kinsler does run well and play very good defense.
3b
NY - Andujar
Bos - Devers
Edge - NY
Yes, I give NY the edge here. Devers has good power and is actually better defensively than Andujar, who makes a LOT of mistakes in the field. But Andujar's bat is terrific, much further ahead in development than Devers right now. I think both will be among the best third basemen in the AL for years to come as they mature, but right now, Andujar is better.
SS
NY - Gregorius
Bos - Bogaerts
Edge - Bos
Slight edge, as Gregorius is definitely a very very good player. But Xander has been a monster this year and is playing great baseball. Very close call but a slight edge to Boston here.
LF
NY - McCutchen
Bos - Benintendi
Edge - Bos
Another slight edge. Benintendi had a solid season - better than McCutchen for sure, but McCutchen has played well for the Yankees (141 ops+ since joining NY). Benny is the better overall player right now, but this is close.
CF
NY - Hicks
Bos - Bradley
Edge - Bos
Very close. Hicks has been really good for NY with 27 homers and a 123 ops+. He comes up big for them and is solid in the OF. Bradley is otherworldly win the OF and even though his overall stat line isn't close to Hicks', since July 1 he's put up a very solid line of .269/.340/.479/.818. If he's THAT kind of hitter, with his defense, he's better than almost any other CF in baseball.
RF
NY - Judge
Bos - Betts
Edge - Bos
Another very close call. Judge is a monster. Absolute monster. Massive home run power, but what catches some people by surprise is that he's fast, he's a good fielder in right, and he has a bazooka for an arm. Just a phenomenal overall player in basically every way. The trouble here is that he's going up against the guy who is basically the best non-Mike Trout baseball player on planet earth. There's literally nothing Betts cannot do. Hits for average. Hits for power. Drives in runs. Great baserunner and base stealer. Insanely good defensively with a very good arm. Right now probably the second best player in the world (he had a better year than Trout but Trout dealt with injuries so I think Trout is still better). Judge is great. Betts is better.
DH
NY - Stanton
Bos - Martinez
Edge - Bos
Another close call. The numbers right now support Martinez as being significantly better, but we all know that Stanton is an animal. Last year's NL MVP, he's finally seeming to get comfortable in NY. None of us would be surprise to see him go off in this series. Still have to give the edge to Martinez but Stanton could easily post better numbers in this series.
Bench
NY - Romine, Walker, Gardner, et al (not sure who they will have exactly)
Bos - Vazquez, Swihart, Holt, Nunez, Pearce/Moreland
Edge - Bos
Pretty close again. I like Boston's bench a little better. Gardner is a great piece for NY and Walker can provide HR power. I like having Pearce or Moreland as pop off the bench, and the Sox' bench is versatile. Holt has been amazing as a pinch-hitter this year.
Starting pitching
NY - Happ, Severino, Tanaka, Sabathia
Bos - Sale, Price, Porcello, Eovaldi
Edge - NY
Sale is obviously the best pitcher of the group, assuming he's healthy and throwing 98 (not 91). The Sox would get to throw him twice if the series goes 5 games. But Price has had problems with NY (fortunately he's not pitching against them in Yankee Stadium) and in the playoffs as a starter in general. So the confidence level for me with him is low. Porcello is a wild card. Eovaldi has had good success against NY but he's also a wild card for me. For NY, Happ is a terrific pitcher and matches up well against Boston. Severino looks shaky to me but obviously has the stuff to dominate. Tanaka is one of those guys who is frustrating to play against because he seems like the kind of guy the Sox should crush but you look up and after 5 innings he's allowed 1 run on just 3 hits. Sabathia I guess would get the nod over Gray and he can be hit hard or be tough. For me, the uncertainty over Sale's health and Price's lack of success in the postseason (and against NY) make me give the edge to NY.
Relief pitching
NY - Chapman, Robertson, Betances, Green, Britton, Cole, Holder, Lynn
Bos - Kimbrel, Barnes, Poyner (?), Wright, Brasier, Rodriguez, Kelly (?)
Edge - NY
Huge edge to the Yankees. The Sox have made some hay against NY's bullpen this year but really, at almost every spot in the bullpen, the Yankees are better - significantly better - than Boston. That's not to say that the Sox can't have bullpen success against NY (or that the Sox can't hit Yankee relievers, because as the post above me points out, the Sox do well against heat), but when evaluating on paper, the Yankee bullpen is way better than Boston's.
Managing
NY - Boone
Bos - Cora
Edge - Bos
I think Cora is a terrific manager and I'm not at all sure that Boone is. Still, in many ways, the players make the managers. A manager makes move X and that guy doesn't come through, and it makes the move look bad. Still...I give the edge to Cora.
Intangibles
Edge - Bos
They have the advantage of having had the best record in baseball, meaning they're the best team in the world over 162 games. They have the best 1-2 punch in baseball in Betts and Martinez. They have home-field advantage. They won the season series over NY 10-9. They don't have the "curse" hanging over them. They seem loose and ready to go. NY has tons of momentum and always seems like a monstrous foe but I think that's more in the heads of fans than the players. Slight intangibles edge to Boston. One thing to look for is the sloppy fielding that NY often displays. They are very capable of giving Boston runs, and when they make mistakes, Boston needs to make them pay for it.
Overall
I give the overall edge to Boston. Obviously the Yankees are more than capable of winning - even dominating - this series, and nothing would surprise me. But the Sox are the best overall team in baseball. If Sale is healthy and throwing in the upper 90s, the Sox have a decided edge. If not, they're in trouble. So we could see the direction of this series in the first two innings of tomorrow night's game.
Prediction
Boston in 5 as Sale comes through big in Fenway to send the Sox to the ALCS. This is gonna be a meat grinder. Big time.