Even before this year’s soft first-quarter domestic box office run came to its end, the comeback cheerleading began: A jam-packed summer of high-profile tentpoles was going to save 2011.

DreamWorks Animation CEO Jeffrey Katzenberg crowed at CinemaCon in March that he “couldn’t be more confident that the summer of 2011 will go down in history as the biggest ever.” Paramount vice chairman Rob Moore took it a step further, reassuring the exhibs gathered in Las Vegas that a gangbusters summer would float 2011 box office to a new record high.

While it may have seemed so at the time, it turns out they weren’t crazy.

B.O. numbers were down nearly 20% year-over-year at the time of those bold declarations, a deficit that looked difficult, if not insurmountable, to erase. Now, with two weeks of summer playtime come and gone — three, if you count the weekend that “Fast Five” bowed — 2011 is down just 12% from the previous year. And summer is doing its part, as 3% of that gap has been closed over the past three frames.

Keep in mind, however, that 2011 is almost $422 million off the pace of 2010. That’s roughly what “Toy Story 3” made ($415 million) during its entire domestic run.

So as this year’s summer lineup readies to launch Stateside, the big question becomes: How well do the season’s pics need to perform to make those glass-half-full predictions come true? The ebb and flow of box office from year to year and season to season is the nature of the beast, but this summer will require a few more ebbs to surpass 2010’s roster of pics.

Over this past weekend, the combined perfs of debuts “Bridesmaids” and “Priest” along with holdover titles “Thor” and “Fast Five” helped weekend totals keep up with, if not run a smidgen ahead of, the comparable 2010 sesh. The weekend before was down roughly 11% from last year, unable to catch the $128 million opening for “Iron Man 2,” but “Fast Five” led a massive 56% uptick over the weekend of April 29.

Now it’s Disney’s opportunity to help turn the B.O. tide, with “Pirates of the Caribbean: On Stranger Tides” set to bow worldwide this weekend. The film is high on most moviegoers’ must-see lists and is expected to open to boffo biz, with tracking suggesting it’ll exceed “Shrek Forever After,” which opened the same weekend last year with $70.8 million. (The “Pirates” franchise’s second installment, “Dead Man’s Chest, opened to $135 million; the third, “At World’s End,” bowed to $114 million.)

Joel Cohen, CEO of Movietickets.com, described “Pirates” — and other forthcoming franchise titles such as “Transformers: Dark of the Moon” — as “home runs.”

“If you look at the upcoming titles, they’re guarantees,” he said, adding that Memorial Day-weekend offerings “The Hangover Part II”and “Kung Fu Panda 2” characterize the summer as ideal counterprogramming. “That’s the most impressive part of this summer. I’ve never seen a summer that’s been put so well together.”

One possible snag for B.O. optimists is that with major releases piled on top of each other all summer long, even the biggest titles won’t have much room to run beyond opening weekend. Studios will need to rely on counterprogramming to afford any breathing room — much like Disney’s “Toy Story 3” was able to play alongside Summit’s “The Twilight Saga: Eclipse,” which launched just two weeks after “Toy” last year.

This year, Disney-Pixar’s “Cars 2” bows the same week as Sony’s R-rated “Bad Teacher,” and a week before Paramount’s “Transformers.” Pics like “Hangover II” and Paramount’s “Super 8,” which bows on June 10 after “X-Men: First Class,” are being tubthumped as potential fanboy-frenzy starters.

That’s important, because success this summer won’t rely solely on how these potential blockbusters open but how they play throughout the season.