The game looked like it was in the bag. The Yankees led the Red Sox 8-3 through six innings on September 6. Boston had its eighth and ninth hitters due up in the seventh, and a foot injury had knocked Jacoby Ellsbury out of the lineup (and leadoff spot). The Yankees just needed to get through that seemingly easy stretch to take a five-run lead to the ninth inning, where Mariano Rivera would loom if necessary.

The Yankees … did not get through that stretch. Boston tallied a run to trim the lead to 8-4, loading the bases with two outs to bring Mike Napoli to the plate. One of the streakiest hitters in the league this year, Napoli was red-hot at the moment, with an opportunity to turn the game with one swing of the bat. On the eighth pitch of the at-bat, Napoli got an offering on the outside corner and drove it to right. In any other ballpark, the ball would almost certainly have been caught, or been at most a double. In Yankee Stadium, however, it was a 335-foot wall-scraper, a grand slam that tied the game 8-8. One inning later, Boston right fielder Shane Victorino, who was nearly as sizzling, cranked a two-run homer to left, giving the Sox a 10-8 lead.

Boston went on to win the game, 12-8, and take three out of four from New York, and now owns the best record in the American League. The Red Sox can count multiple reasons for their worst-to-first comeback this season. Yet the factor that has loomed larger than all the others was also the most heavily criticized by skeptics who doubted Boston’s ability to contend this year: Napoli, Victorino, and the rest of the team’s passel of midlevel free agents.

The Red Sox were more aggressive in their pursuit of free agents than any other team last winter. They failed to land the two biggest names on the market, ceding Josh Hamilton and Zack Greinke to SoCal suitors. But they did pursue and land several players in the next tier, at prices that befuddled many observers. When the Red Sox talked up their new crop of signees as “character guys,” most had to wonder if that was code for “players who stink at baseball but are pleasant to be around.” Instead, with one exception, those moves have worked out spectacularly well, propelling Boston to an 8½-game lead in the AL East.

The Bargain Overbid

The Victorino signing drew arguably the most criticism, but wound up being crucial to Boston’s success. Going by advanced metrics or even scouting consensus, Victorino has made a strong case as the best defensive right fielder in baseball this season, while playing in one of the quirkiest parks for any right fielder to cover. By both Defensive Runs Saved and Ultimate Zone Rating, Victorino grades out as saving more than 20 runs above what the average right fielder has done this year, while often making spectacular plays. So while multiyear samples are always preferable when looking at advanced defensive stats, this season’s numbers suggest that Victorino has added at least two wins to Boston’s ledger with his defense alone.

Moving a skilled center fielder to a less demanding corner position invites the possibility of a big defensive season. Victorino’s offensive contributions this year have been a bigger surprise, however, especially his recent power surge. Because of a nagging left leg injury and what Sox manager John Farrell simply described as “feeling better” with the new approach, Victorino ditched his career-long practice of switch-hitting in favor of exclusively batting right-handed. He made the change on August 4, and didn’t see particularly great results at first. But since August 17, Victorino has been unconscious at the plate, swatting seven homers and six doubles in 21 games, while hitting .357.

Those numbers stand in stark contrast to last year’s ugly offensive season, in which Victorino hit just 11 homers, batting .255/.321/.383. When Victorino signed his three-year, $39 million deal in December, Boston fielded criticism for giving a mediocre hitter that much money. The combination of Victorino’s defense and baserunning figured to make him something like a two-win player even in a worst-case scenario, however. And considering the going rate for free agents sits at about $6 million per win, the Sox could have reaped a respectable return even if Victorino’s bat failed to resurface.

It turns out the 2012 season was not the beginning of the end for the player in his age-31 season, though. It was simply a down year, and a reminder that players’ stat lines aren’t always perfect bell curves; there are random dips and spikes along the way. With Victorino producing 18 percent better than average this year while bringing stellar defense, stealing 20 bases, and providing generally impactful baserunning, he’s been more like a five-win player, and Boston’s second most valuable player in 2013.

The Streaky Smasher

The Sox and Napoli initially agreed to a three-year, $39 million contract (identical to Victorino’s) during the winter meetings. A physical uncovered problems with the labrum in Napoli’s hip, however, leading many to wonder how Boston could lay out that much money for a slugger who might be damaged goods. The two parties renegotiated the deal down to one year for $5 million. It was a relatively small outlay for a team like the Red Sox and a player with Napoli’s power-hitting track record, and such a huge reduction from the original deal that it made people question how much Napoli would really be able to contribute this season.

Turns out, a lot. Napoli’s contract came with the opportunity to make up to an additional $8 million, and Boston’s first baseman is going to collect on a lot of those incentives. He was a terror to start the year, hitting .287/.342/.602 through May 1 while also coming through in big spots, knocking in 31 runs in 27 games. Napoli’s RBI opportunities and numbers both tumbled over the following three-plus months, as he hit just .231/.335/.369 from May 2 to August 13.

He’s been a house afire since then, hitting .356/.449/.814 with seven bombs in 14 starts, and delivering one stretch in which he reached base nine consecutive times. Napoli has out-homered Hamilton this season, despite snagging 41 fewer plate appearances and getting $120 million less in guaranteed money than the Halos gave their power-hitting buy last winter.

The Force of Nature

Though his value is inherently limited because he’s a relief pitcher, Koji Uehara’s numbers smack one in the face in a way that Victorino’s and Napoli’s simply don’t. That’s because Uehara is having one of the best per-inning seasons of any reliever in MLB history.

Uehara had his own share of detractors when the Sox signed him to a one-year, $4.25 million deal with a vesting option to double the years and money. There was no doubting Uehara’s ability coming off a season in which he posted a 1.75 ERA and 2.40 FIP, and certainly not given his career eight-to-one strikeout-to-walk ratio, the highest in major league history for a pitcher with as many innings pitched. The doubt came because those innings were always limited by injuries. Boston penciled in Uehara as someone who could pitch one strong inning at a time but go no more than three times or so per week, with the hope that Uehara could last longer in 2013 than he had in the past. Those durability concerns led Farrell to choose not one, not two, but three other pitchers to close games earlier this season. When Joel Hanrahan and Andrew Bailey both suffered season-ending injuries and a plan to use Junichi Tazawa in the ninth failed to ever really get going, Uehara finally got the call.

Here’s what he’s done since:

• Since the beginning of July, Uehara has struck out 42 batters, walked two, allowed eight hits, and posted a 0.00 ERA in 31⅔ innings pitched.

• He’s retired the last 31 batters he’s faced, the equivalent of a perfect game with another 1⅓ innings thrown in for good measure.

• Per Rotowire’s Jason Collette, Uehara has faced 383 right-handed batters since the start of the 2010 season. He’s walked six of them while recording twice as many strikeouts (129) as hits allowed (64).

Pitching as regularly as a typical closer has not been a problem. Even going on consecutive days has worked out great. Thanks largely to his unhittable splitter, Uehara is on pace to post a 0.58 WHIP, which would be the lowest mark ever for a pitcher with 60-plus innings pitched in a season. Even granting that WHIP is more useful as a fantasy stat than an analytical stat, and that WHIP’s hit component is subject to defense- and luck-related influences, anytime we can use the word “ever” to describe a pitcher’s dominance, it’s probably a really good sign.

The Steady Eddie

Those who criticized Boston for inking Stephen Drew to a one-year, $9.5 million deal fell into some of the same analytical pitfalls they did with the team’s other 2012-13 signees: They ignored Boston’s ability to absorb a near-10-figure contract, they discounted the fact that $9.5 million isn’t much money in today’s market, and they placed too much emphasis on Drew’s most reason season, much like they did with Victorino.

In Drew, the Red Sox got a capable defensive shortstop who, when healthy, could produce roughly average offensive results. Given how tough it is to play short every day and both field and hit effectively, a player who can do both is a valuable commodity. Drew has delivered on both fronts this year, batting .244/.327/.429 after a rough start to the season while flashing a better-than-average glove.

Moreover, Drew’s presence probably didn’t hurt in Boston’s decision to trade younger shortstop Jose Iglesias for a year-plus of top-flight starting pitcher Jake Peavy. Yes, watching Iglesias make spectacular plays in Detroit for the next half-decade could sting at times. But with Peavy filling the team’s only obvious major weakness, Drew might have indirectly helped pave the way for a World Series title this year. Not bad.

The Bearded Battalion

To be fair, any player not sporting a beard this year is probably ineligible to show his clean-shaven face at Fenway. Still, the signing of Jonny Gomes and more or less free acquisition of Mike Carp have worked out well for a Red Sox team that recognizes and exploits the importance of the platoon advantage.

The Gomes deal caught more flak than the Carp move, since it was a two-year, $10 million commitment to a player perceived as a one-dimensional benchwarmer. Granted, Gomes is hitting just .212 this season against left-handers, a near-Mendoza performance at what was supposed to be his primary function. But at age 32, Gomes continues to find other ways to get on base, racking up a more respectable .333 OBP against southpaws. What truly stands out, though, is his power and the timing of his home runs this year. Gomes has launched seven homers and nine doubles in just 146 at-bats against lefties. He’s become a walk-off master, too, toppling the Padres and Rays with blasts over the Monster (both against right-handed pitchers). Gomes is a prime example of how a team with Boston’s financial muscle can spend its money in multiple fruitful ways, whether by extending a franchise player like Dustin Pedroia or by giving a part-time player like Gomes a relatively lucrative free-agent deal.

Carp’s making more or less the league minimum, so no one questioned the expenditure in his case. But he had earned a reputation with the Mariners as something of a Quadruple-A player, a guy with good minor league numbers who never seemed to do much in the big leagues. All he’s done in Boston is hit .310/.371/.545 in 210 plate appearances. Granted, a big chunk of that performance has been fueled by a flukish and unsustainable .410 batting average on balls in play. But even regressing that number, Carp has been a steal and a half at $508,500 this year.

The One Miss

On a strict dollars-to-WAR basis, Ryan Dempster looks destined to be a disappointment for the Sox. In the first season of a two-year, $26.5 million pact, he’s posted a 4.79 ERA and 4.69 FIP. His past nine starts have been downright dreadful, with Dempster putting up a 6.39 ERA. Still, there’s something to be said for a pitcher making 27 starts and tossing 157⅔ innings, even if a bunch of those innings haven’t been all that good. We’ve said it many times before and we’ll say it again: Make up all the fried chicken and beer excuses you want, but the bottom line is that the 2011 Red Sox make the playoffs if they don’t have to lean on Andrew Miller, Kyle Weiland, and a washed-up Tim Wakefield to bail out their decimated rotation in September of that year.

This season, Dempster at the very least held the fort for a while until Peavy came over via trade and Clay Buchholz rehabbed from injury. Short of a natural disaster, there’s no way in hell Dempster will start a single playoff game for the Sox. His role with the team looks uncertain for next year, and that’s with $13.25 million left on his deal for 2014. But the Sox have a bottomless pit of resources, meaning they can afford to give a moderate two-year deal to an innings-eater who’ll keep them miles away from the Weilands of the world, and gladly live with that relatively harmless overpay.

The Result

With 16 games to go this season, the Red Sox are on pace to win 98 games. That would mark an improvement of 29 games over last year, tying the 1991 Braves and falling just shy of the 2008 Rays on the short list of the best year-over-year turnarounds. This wouldn’t have happened without (mostly) healthy performances from Ellsbury, Pedroia, and David Ortiz, a huge comeback from John Lackey, and numerous other factors. But it also definitely wouldn’t have happened without a handful of free agents who were touted as little more than clubhouse stabilizers.

Turns out those stabilizers can play a little ball, too.