Galaxy’s Bruce Arena has to find the right mix

No one knows whether Bruce Arena is a fan of high-wire acts, but the Galaxy coach might become one before the end of the 2011 Major League Soccer season.

He has to balance a roster that, from an age standpoint alone, looks like two halves of a broken seesaw, with the experienced but well-aged on one side and the young but inexperienced on the other.

The twilight set:

Gregg Berhalter, 37; Frankie Hejduk, 36, Juan Pablo Angel, 35; David Beckham, 35; Jovan Kirovski, 34; Donovan Ricketts, 33, and Todd Dunivant, 30.

The nursery:

Jack McBean, 16; Michael Stephens, 21; Brian Perk, 21; Pablo Cardozo, 21; Juninho, 22; Leonardo, 22; Omar Gonzalez, 22; Hector Jimenez, 22; Miguel Lopez, 22, and A.J. DeLaGarza, 23.

McBean became the youngest member of the Galaxy on Wednesday when the U.S. under-17 national team forward from Corona del Mar High was signed, along with Lopez, an attacking midfielder from Quilmes in the Argentine league.

The Galaxy also added a member to the coaching staff.

Curt Onalfo, who played for four years under Arena at the University of Virginia and later was coach of the Kansas City Wizards (now Sporting Kansas City) and of D.C. United, has been brought aboard to replace Cobi Jones. Onalfo, 41, will have charge of the Galaxy reserve team.

A more pressing concern for Arena than the age factor is how to balance the playing time now that he has enlarged and strengthened the roster from a team that reached the MLS final in 2009 and the conference final in 2010.

Suddenly, there appear to be more players capable of starting than there are places available on the field.

Does Arena play a lone striker up front in a 4-2-3-1 formation or does he use two forwards in a more traditional 4-4-2 lineup?

With the high-scoring Angel on board as the third designated player with Beckham and Landon Donovan, the Colombian is certain to start.

But who plays alongside him — holdover Mike Magee or newly acquired Chad Barrett, Adam Cristman or even McBean? And how does Donovan fit into the mix?

“My guess is we would try to play two [forwards],” Arena said. “There’s a bunch of options we would have. We always have the possibility of playing with three when you think about putting Donovan up there with Angel, and Barrett could play wide, Lopez could play wide.

“We’re going to play around with that a little in the preseason, but there are times in the season when you have injuries and you have to create different ways to align your team, so we can’t rule anything out. But my preference when Angel’s on the field is for him to have a partner.”

The Galaxy opens at Seattle on March 15.

“I think we’ve done a good job in the off-season trying to improve our team and hopefully you’ll see that during the season,” Arena said.

“With the addition of the CONCACAF Champions League and the U.S. Open Cup, we’ll probably play about 42 games. … Depth is going to be critically important.”

grahame.jones@latimes.com