BOSTON — John Farrell doesn’t like to talk about the postseason – not in September, not when his team’s lead over the Yankees is 3 games, not when he continually preaches a focus on the next game and only the next game to his club.

But even Farrell could acknowledge over the weekend that he’s viewing the final three weeks of the season through the lens of the playoffs.

As the Red Sox reach the home stretch of their season, Farrell is gauging who best fits his potential postseason roster.

“That’s going on currently in my mind with every phase of our team,” Farrell said of competition on the roster. “Our bullpen, there are some guys stepping up and throwing the ball very well right now. And if that point in time comes where we move on, yeah, you begin to play a little closer attention to the hot hand when certain roles are being filled.

“So, whether it’s position players, an extra guy on the bench, a guy in the bullpen – all that is being closely watched right now.”

With that in mind, let’s imagine the postseason roster as a kind of NCAA tournament field. With 20 games to go in the regular season, who’s definitely in, who should be in and who’s on the bubble?

ROTATION

LOCKS: Chris Sale, Drew Pomeranz

SHOULD BE IN: Rick Porcello

BUBBLE: Doug Fister, Eduardo Rodriguez, David Price

Sale and Pomeranz remain in line to start Games 1 and 2 of a postseason series – and one imagines possibly Games 4 and 5 of the same series, with Sale going on three days’ rest if needed.

Beyond that, Porcello’s pedigree from last season keeps him on the inside track for a spot, so long as he’s not objectively outpitched down the stretch by both Fister and Rodriguez. At the moment, Fister has a clear step up on Rodriguez. Not only has he pitched much better over the last month, but he also has legitimate postseason experience.

Farrell mentioned the hot hand, though, and Rodriguez still has a handful of starts to pitch himself back into contention the way Clay Buchholz did a season ago. Buchholz, who didn’t rejoin the rotation until Sept. 6 last year, pitched to a 1.42 ERA in his last three starts, moving ahead of Pomeranz and Rodriguez on the depth chart to start Game 3 against Cleveland.

The uncertainty regarding Price hovers over this group, as well.

Should Price have the time to work his way back as a starter – and I’m doubtful he does – he could bump someone else from the quartet.

BULLPEN

LOCKS: Craig Kimbrel, Addison Reed, Brandon Workman, Joe Kelly

SHOULD BE IN: Matt Barnes

BUBBLE: Robby Scott, Carson Smith, Heath Hembree, Fernando Abad, Blaine Boyer, Austin Maddox, Price

How Farrell leverages his stalwarts late in the game – Kimbrel, obviously, but also Reed and perhaps Workman – may determine how deep the Red Sox go in October. Kelly was outstanding last postseason, and he’s proven particularly successful against the Indians – still Boston’s likeliest first-round opponent.

Barnes has struggled over the last month and spent time on the disabled list; provided he looks anything like he did in the first four months of the season, he’ll be part of Boston’s middle relief corps. Smith has the best stuff of anyone in this group, but he’s barely pitched the last two seasons. He’d probably have to look dominant this month to have a chance.

On Saturday, Farrell specifically mentioned the strong recent performance of Maddox since his September call-up; however, Maddox has a lot of ground to make up if he wants to surpass someone like Barnes for a spot.

From the left side, while Scott has had his ups and downs throughout the season, he’s still holding left-handed hitters to a .121 average and .511 OPS.

Again, Price could be a factor here. If he’s healthy enough to pitch but doesn’t have the time to build his arm strength back to start, he could be a very intriguing weapon in the middle innings. If he’s not in the rotation, Rodriguez could be an option here as well; he was sharp in a one-off relief appearance back in April.

The Red Sox would also have to decide whether to keep 11 or 12 pitchers for the playoffs; each of the two times they’ve made it under Farrell, they’ve kept the staff to 11 and added an extra position player.

That would limit space for Hembree and Boyer, who haven’t seen many high-leverage spots of late, or Abad, whom Farrell hasn’t seemed to trust in key spots all season.

BENCH

LOCKS: Eduardo Nunez, Sandy Leon, Rajai Davis, Chris Young

SHOULD BE IN: Brock Holt

BUBBLE: Deven Marrero

The Red Sox have 10 regulars for nine spots, with Nunez serving an all-purpose role worthy of an everyday spot somewhere. Leon is the obvious backup to Christian Vazquez, and he’ll probably start behind the plate whenever Sale is on the mound. Davis was acquired to be a postseason weapon on the bases, and Boston’s unwillingness to promote Bryce Brentz this month to challenge Young suggests his position as a lefty masher is safe, even if he hasn’t mashed lefties all season.

The presence of Nunez means the Red Sox don’t have to keep an additional infielder, though they almost certainly would. Holt has the obvious leg up given his track record with the team over the past few seasons, including a strong Division Series last year. But should the Red Sox prioritize defense – to replace Nunez or Devers on the infield – Marrero could be an option.