Will Beckett be the difference-maker?

Josh Beckett makes his return Friday from the disabled list more than two months since last taking the mound for the Boston Red Sox. Much happened in those 65 days, but the Red Sox enter Friday just a game and a half closer to first place.

Is Beckett's return the equivalent of acquiring an ace at the deadline? Can a healthy rotation keep the team in the race until the bats come back? Here are five things to ponder as Beckett tries to right the ship.

1. The losing-streak stopper

What constitutes a staff ace? Sure, he has to be a dominant pitcher, but there's another common attribute: a momentum changer. In other words, a true ace snaps a losing streak.

From that standpoint, there was no one better than Beckett in 2009. Following a loss, Beckett was 8-1 last season. According to the Elias Sports Bureau, that was tied with Matt Cain for the best winning percentage in the majors following a team loss (minimum nine decisions).

Beckett's effectiveness goes beyond his own win-loss record, as he continually gave the Red Sox a chance to win. As a team, the Red Sox were 12-3 when Beckett took the mound after a loss, the best team winning percentage for any AL starter in those situations, according to Elias. To put that in perspective, the Red Sox were just 25-27 in all other such games.

Entering Friday, Boston is 23-19 following a loss in 2010, but no one has emerged as Beckett's momentum-turning replacement. Clay Buchholz (5-3) has been the closest thing. Tim Wakefield, Beckett's replacement in the rotation, is just 1-2, and Boston is 2-3 overall when he starts following a loss.

With 10 losses in their past 15 games entering Friday, the Red Sox need a dramatic change in energy.

A healthy Beckett could provide just that.

2. The long road ahead
Just 24-22 on the road, the Red Sox pale in comparison to their division rivals. Road success separates the Yankees and Rays from the pack, and is the biggest reason they sport the two best records in baseball. At 31-17, the Rays are the best road team in baseball, while the Yankees (28-19) are a close second.

Here's another way to look at this. Looking at just home records, the Red Sox would be a game and a half behind the Yankees and two games up on the Rays. But in the only standings that count, they trail the Yankees by seven games and the Rays by four.

With injuries finally catching up to them, the Red Sox's postseason hopes suddenly teeter on the edge. Boston is certainly not helped by its schedule. No American League team has more road games remaining than the Red Sox.

Just four games into a stretch that puts them on the road for 20 of 27 games, Boston needs to turn its season around away from the ballpark in which it was built to succeed.

Enter Beckett.

From 2006 to 2009 -- Beckett's first four seasons in Boston -- he was a better pitcher away from Fenway, posting a 34-17 record with a 3.61 ERA on the road. Over that span, only Carlos Zambrano (35-11) had more road wins.

Over that same stretch Beckett was 31-17 at home with a 4.47 ERA, numbers significantly aided by a 10-1 mark at home in 2009.

With four of his first five post-DL starts away from Fenway, the Red Sox will be counting on Beckett's record of road success to keep them in the race.

3. Remembering what the Red Sox have
Going into the season, the Red Sox had arguably the best top three starters in the league. Just think, that didn't even include 2010 All-Star Buchholz.

Beckett, Jon Lester and John Lackey were supposed to be as intimidating a front end of the rotation as you could find. Just half a season later, that perception appears lost. Nothing more could be asked of Lester, but between Beckett's injury and Lackey's inconsistency, that respect will need to be earned back.

At the same time, three up-and-down months does not change the unmatched big-game pedigree of the Red Sox rotation. That is to say, perhaps the rocky introduction has clouded our collective memories.

In Beckett, Lester and Lackey, the Red Sox boast three pitchers who have started and won the deciding game of a World Series. According to Elias, there have been only seven previous teams that could make that claim, and none in 64 years. In 1946, Red Ruffing, Spud Chandler and Tiny Bonham all pitched for the Yankees. The difference? All three were older than Lackey, who at 31 is the oldest of the Red Sox trio. In fact, Ruffing (41) and Chandler (38) alone were nearly as old as Boston's three.

In Beckett (13 postseason starts) and Lackey (12), the Red Sox have unmatched postseason experience for a pair of relatively young starters. You'd have to go back to Catfish Hunter and Ken Holtzman of the 1970s A's to find a duo of starters age 31 and under with equivalent seasoning.

Of course, postseason experience means nothing if you finish in third place. After April's false start, the Red Sox finally get to see what they have in their World Series heroes, all of whom are locked up until 2014. With the offense still banged up, it's the rotation that needs to carry the Red Sox into August.

4. The impact of Beckett's absence
While replacing Beckett in the rotation, Wakefield was 3-6 with a 5.75 ERA. In his 11 starts, the Red Sox were just 4-7.

So how much did Beckett's injury cost the team in the win column?

You may have heard of WAR (wins above replacement), a statistic used to measure the overall impact a player has on his team's success in comparison to a replacement-level player.

Well, in this case, we know who replaced Beckett. So let's create our own statistic, one that has no mathematical correlation to WAR. But let's still call it WAW -- wins above Wakefield.

AccuScore.com ran 10,000 simulations replacing Wakefield with a healthy Josh Beckett. The Red Sox averaged 5.6 wins, or 1.6 wins above Wakefield.

However, even that may be an underestimation. The pitcher who posted a 7.29 ERA in eight starts is not the real Josh Beckett. However, those numbers were included in the simulation.

How would the Red Sox have fared with the 2009 version of Josh Beckett making those 11 starts? AccuScore again ran 10,000 simulations, this time disregarding his 2010 numbers. Here, Boston averaged 6.1 wins, giving Beckett a 2.1 WAW over that span.

Now, two wins may not seem like much, but consider the impact on the playoff race. Entering Wednesday, AccuScore gave the Red Sox a 20.1 percent chance of making the postseason. Add in those 2.1 wins and that number almost doubles to 37.2 percent.

5. What to watch for
Everything noted above shares a common assumption: The Josh Beckett returning on Friday will be the 17-game winner from 2009. But that's not who we witnessed over the first six weeks of the season, when Beckett posted a 7.29 ERA.

It's difficult to say how much of that was related to injury. It's also probably worth noting that Beckett had a 7.22 ERA through five starts in 2009. Regardless, it's clear that Beckett was not the same pitcher prior to going on the DL.

Some of the differences were blatant. Beckett was striking out fewer batters, while issuing more walks. His 2.1 strikeout-to-walk ratio would be the lowest of his career.

He did little to take advantage of the improved infield defense. His 37.6 ground ball percentage was substantially lower than last season's 47.5.

There does appear to be at least one common trend to these struggles: His changeup.

In 2009, opponents hit just .191 on at-bats ending with a changeup. This season, it's up to .500. That includes a .563 mark against lefties, who hit just .171 against the pitch in 2009.

Beckett allowed only four extra-base hits off his changeup last season, but has already allowed three in just eight starts in 2010. Meanwhile, after fanning 17 on the changeup in 2009, he's yet to do it once this season.

That decreased ground ball percentage? Go ahead and blame the changeup for that, too.

Last season, Beckett had a 70.8 ground ball percentage with the changeup, according the Inside Edge, significantly higher than the league average which rests around 48 percent. This season, it's just 35.0 percent, and location is part of the reason.

Most effective when he throws it low and away, Beckett did so with 45 percent of his changeups last season. This season, Inside Edge puts that number at 27 percent, and a significant number of changeups were left up in the zone.

For a team relying on him to change up the momentum, it's Beckett's changeup that may hold the key.

Jeremy Lundblad is a researcher with ESPN Stats & Information. He provides statistical analysis for ESPNBoston.com. ESPN Stats & Information's John Parolin contributed to this story.