BOSTON – Monday was a day of Fenway Park returns.

The Sox returned home for the first time since the All-Star Break after taking two of three in St. Pete.

Carl Crawford returned to Boston for his first big-league game of the season.

Jacoby Ellsbury returned to center field at Fenway for the first time in more than three months.

Kevin Youkilis returned to the place he called home for eight and a half seasons.

Yes, there are plenty of story lines to follow during this four-game set between the Sox and the Sox.

Yet one of the biggest returns of all happens tonight.

Jon Lester will be back on the mound for the first time since an ugly 7-3 loss to the New York Yankees in the final game before the All-Star break.

Lester lasted just 41/3 innings that night, giving up five runs (four earned) on nine hits. It was the fifth time in his last 10 starts that Lester gave up four or more runs in a game.

He needs to be better than that.

Lester’s 5.14 ERA in those five starts is too high. Far too high. The Red Sox have lost six of those 10 starts. In fact, they’ve lost 11 of Lester’s 18 starts this season.

We all know that wins and losses are not a true measure of a pitcher’s effectiveness. Seattle’s Felix Hernandez reminded us of that in 2010 when he won the Cy Young Award despite a 13-12 record.

Voters understood that his 2.27 ERA and 1.057 WHIP over 249 innings were the numbers that matter.

Still, an ace is supposed to give his team a chance to win when he takes the mound. And teams have to take advantage of those chances.

That Seattle team was .500 when Hernandez started in 2010, a far cry from the 44-84 record they posted the rest of the season.

In 2012, the Red Sox have been in search of an ace. They are 13-20 in games started by Lester and Josh Beckett.

Those two pitchers were supposed to be the dual anchors of the rotation, the horses that would lead the team through the challenges of a season filled with injuries.

Instead, the two have been part of a rotation that has posted a 4.77 ERA this season, the fourth-worst in all of baseball. That number needs to get lower.

It was on the way to getting much higher on Sunday after Beckett gave up three runs in a 26-pitch first inning against the Rays. Yet he settled down, throwing five scoreless innings after that and turning in a quality start for his first win since May 20th.

The Sox are getting closer to becoming the team they expected to be this winter.

Jacoby Ellsbury returned from the disabled list in St. Pete, and had six hits in three games against the Rays.

Will Middlebrooks didn’t go on the DL but missed seven games with hamstring issues. He had three hits on Sunday and had four RBI in the series. Crawford is finally back. Dustin Pedroia is expected back by week’s end.

Those bats should help a lineup that was sagging under the weight of injury heading into the break. Boston averaged just 3.1 runs a game in the final 11 games heading into the All-Star Game.

Still, the Red Sox offense has scored the second most runs in the majors. Hitting hasn’t been the issue for much of this season. Starting pitching has been.

And, starting tonight, Jon Lester has a chance to do something about that in his return to the mound.

Tom Caron is the studio host for Red Sox broadcasts on the New England Sports Network. His column appears in the Press Herald on Tuesdays.