After a week of waiting since it was first reported that the Red Sox had come to terms on a five-year deal with J.D. Martinez, Boston announced a contract with the slugger Monday. And as you've probably heard people say all offseason, it's a perfect match of player and team need. The reason people have been saying that is because the Red Sox hit the fewest home runs in the American League in 2017, and Martinez, well, hits a lot of home runs (45 in 489 plate appearances last year). In a baseball world where homer records were being shattered regularly, the Sox actually hit 40 fewer home runs in 2017 than they had in '16. It's not what you want.
Boston didn't have a single batter hit 25 home runs, one of only three teams to fail to do so. (The other two, Philadelphia and San Francisco, lost 96 and 98 games, respectively.) It was the first time in a quarter-century the Red Sox didn't have a 25-homer hitter, dating back to the 1992 Sox of Tom Brunansky and Jody Reed. 
Based on that, it's easy to think that the 2017 Red Sox offense was a completely ineffective group, though that's not really true, and so you might be shocked to learn that despite returning largely the same roster, the 2018 Sox hitters look like they could be good. Really good, actually -- according to FanGraphs, Boston's 2018 lineup is projected to score the third-most runs per game in baseball.

Realize how good "third place is," when you take note of who's ahead of them. The Astros may very well have one of the best lineups in history, the Yankees might possibly break the all-time home run record, and there's the Red Sox right there with them.
If this sounds completely shocking, it shouldn't be, largely because the Red Sox were a little better than you think they were last year. Though the power outage was real, the offense last year was good enough to win the AL East and finish 10th overall in runs scored.
Obviously, the addition of Martinez is going to help, since he's been one of the 10 best hitters in the game over the past four seasons, and he'll take away plate appearances that last year often went to Chris Young and Hanley Ramirez, who each underperformed. He's already projected to be Boston's best hitter. But for as much as Martinez will add, this isn't really a story about him. This is about the expectations for the young hitters the Red Sox already had taking steps forward -- or in some cases, back to "normal."

Start with Xander Bogaerts, who had what looked on the surface to be a very disappointing 2017, compared to his previous two years.
2015: .320/.355/.421 (111 wRC+)
2016: .294/.356/.446 (115 wRC+)
2017: .273/.343/.403 (96 wRC+)
That's bad, right? All three of Bogaerts' triple-slash line stats fell, especially his power. Now how would you feel if his 2017 line actually read .308/.363/.455 (114 wRC+) instead? You'd probably say that Bogaerts was doing the same thing he does every year. That's what he was hitting on July 6 when he was hit in the wrist by a Jacob Faria pitch; playing through the injury, he hit only .232/.321/.340 (74 wRC+) for the rest of the season.
"To a point, I do regret [playing through pain], but it's over with," Bogaerts told MLB.com earlier this month. "We were in the heat of things, we were pushing for the playoffs. You don't want to be the guy on the bench not being able to help your team to win. You learn, and I definitely did."
Bogaerts is projected to hit .287/.350/.439 (107 wRC+), a very reasonable expectation based on his pre-injury performance.
You can write almost exactly the same thing about Mookie Betts, who had what seemed, on the surface, to be a poor season -- by his standards.
2015: .291/.341/.479 (120 wRC+)
2016: .318/.363/.534 (137 wRC+)
2017: .264/.344/.459 (108 wRC+)
What happened there? Like Bogaerts, Betts was playing through a hand injury, in this case his thumb.

"It's been going on for a couple months, but I was able to just kind of play through it," Betts said when he was forced to come out of a game against the Rays in September due to a thumb contusion.
We don't know exactly when Betts first injured himself, but the stats tell a pretty clear story. Through the end of June, he hit .280/.356/.490 (119 wRC+). From July 1 on, Betts hit .248/.332/.427 (96 wRC+). It's the difference between hitting like Francisco Lindor or, well, Bogaerts.
If you believe that the pair are healthy, then you almost certainly believe they're going to perform like they did in the past.
In addition, there's the potential for approach changes, given that the Red Sox have a new manager in Alex Cora and a new hitting coach in Tim Hyers. Boston hitters were almost infamously passive in 2017, perhaps to their own detriment. Between them, Betts (642) and Bogaerts (585) watched over 1,200 in-zone pitches go by without swinging, making them two of the top six in baseball in terms of watching strikes go by.
There's something to be said for patience and discipline, but there's also something to be said for seeing your pitch and crushing it. Cora made that very clear when he arrived in Boston last fall.
"I think the key of the offense is to have a consistent approach, hunting pitches you can do damage with," Cora said at his introductory news conference. "First pitch or a 2-0 pitch. Sometimes a first pitch available is the one you can do damage on, so we're going to have guys ready to do damage early in the count, regardless."
Cora specifically noted Betts and Bogaerts, too, saying "these guys are going to take a step forward. We're going to preach them to be aggressive."

In addition, Boston will get the benefit of a full season of young sensation Rafael Devers, who had a smashing debut (.284/.338/.482, 111 wRC+) and is projected for more of the same (.280/.331/.485, 110 wRC+). Last year, he had 236 plate appearances at third base, while 308 went to the trio of Deven Marrero, Pablo Sandoval and Josh Rutledge.
You can dream on improvement from 23-year-old Andrew Benintendi, who was essentially league-average in his first year (.271/.352/.424, 103 wRC+). You can hope that the steps catcher Christian Vazquez took to become only slightly below-average (.290/.330/.404, 93 wRC+) stick, or that Ramirez is healthy enough to look more like 2016's star (.286/.361/.505, 128 wRC+) rather than '17's disappointment (.242/.320/.429, 93 wRC+), or that Jackie Bradley Jr. looks more like the very good first-half player (.280/.363/.490, 122 wRC+) and less like his second-half disaster (.204/.277/.302, 51 wRC+).
There's uncertainty here, because there always is with every team. But Martinez is an elite slugging star, and the Red Sox aren't starting from such a low spot as the 2017 home run total might have you otherwise think. This is a talented young lineup, held back by injury last year. With health, a new coaching approach, and a new slugger, this might be more than just a good lineup. It might be one of baseball's best.