Eduardo Nunez could be critical playoff piece for Sox - if he's healthy

There may be no more important player in the Red Sox lineup this postseason than Eduardo Nunez.

What’s troubling is that there may no player in the Red Sox’ lineup whose health is more of a question mark than Eduardo Nunez.

Last month Nunez suffered a strained posterior cruciate ligament in his right knee. Then, on the first night he returned to the lineup last week, he aggravated the knee when his spike got caught in the dirt near home plate.

Wisely, the Sox held Nunez out for the rest of the final week of the regular season, allowing him to focus on rehabbing the knee and strengthening the muscles around it. After increased activity over the weekend that saw him take ground balls on the field, some live batting practice and baserunning drills, Nunez was expected to go through some work on Monday at Fenway, to better replicate game conditions and intensity.

As recently as Sunday, John Farrell expressed confidence Nunez would be healthy enough to include on the 25-man roster for the AL Division Series against the Astros which begins Thursday.

But, Farrell cautioned, he was unsure whether Nunez would be healthy enough to play the field during the series.

The Sox had better hope he can, since a healthy Nunez could go a long way in making the offense more productive.

Surely, it can’t be a coincidence the Sox began to take off as a team just as Nunez arrived. After being obtained days before the deadline for two low-level pitching prospects, Nunez made his debut on July 28.

At the time, the Red Sox were 56-47, a winning percentage of .544. After his arrival, the Sox were 37-22 the rest of the way, good for a .627 winning percentage. Even if you limit the sample to only games Nunez started, the Sox were 23-15 for a .605 winning percentage.

He served as an adept table-setter, usually hitting in one of the top three spots in the order. He added another stolen-base threat with six steals in eight tries. (For the season, Nunez was 24-for-31 in stolen base attempts).

But Nunez was more than an on-base piece with speed, as his .518 slugging percentage with the Red Sox indicates. He had 20 extra-base hits in 38 games, exceeding the Red Sox’ own expectations.

“The thing about it was, he transitioned so quickly,’’ said John Farrell. “He was swinging the ball so well for the Giants before the trade. He exceeded the power, maybe, that we anticipated. But as far as the quality at-bats, the hard contact — we knew were acquiring a good player — but the frequency with which he drove balls out of the ballpark? That probably exceeded (what we thought we were getting).’’

After hitting just four homers for the Giants in 76 games with San Francisco, he blasted twice as many (eight) in half as many games (38) in Boston.

Nunez played three infield positions (second, short and third) with the Sox along with a few games at DH. But lingering concerns about the trustworthiness of his right knee could limit him to either DH or pinch-hitting duty in the ALDS.

That would be problematic for Farrell. It would be advantageous to have him available to play a game at second, if only to further protect Dustin Pedroia, who’s dealing with a balky knee of his own. Additionally, it wouldn’t be hard to imagine the manager wanting Nunez at third base over Rafael Devers against presumed Game 2 Houston starter Dallas Keuchel, a lefty.

If Nunez is restricted to DH, it would seem to prohibit Hanley Ramirez from being in the lineup other than in Keuchel’s start. Farrell has already committed to having lefthanded Mitch Moreland as his starting first baseman against right-handed pitching.

That, in turn, forced him to choose between Nunez and Ramirez as his DH, and while Nunez has clearly been the more consistent hitter, not having Ramirez (except for late-inning pinch-hit opportunities) further depleted a lineup already lacking in home run power (Ramirez’s 23 homers placed him second to Mookie Betts, who had 24).

For much of Nunez’s first six or so weeks with the team, he was a versatile piece who could move around the infield and replace injured players or provide rest for tired ones.

Now it’s Nunez’s turn to fit in where he can and when he can, health permitting.