Califf and Michael Orozco Fiscal were the main central defenders in 2010, but one of them will be moving, because Valdes will occupy one of the spots.
Orozco Fiscal can play as an outside back or even in the midfield, while Califf says his only spot is in the middle.
Even if Orozco Fiscal were to move to an outside back position, it would mean players such as Jordan Harvey and late-season acquisition Sheanon Williams could be battling for one spot.
Harvey started 29 games and led the team with 2,960 minutes played. Williams started eight games and played well after being signed Aug. 31 from the Union's USL-2 affiliate, the Harrisburg City Islanders.
So if Orozco Fiscal stays on defense, somebody with experience will play in a reserve role.
The Union began figuring things out during their first workout on Monday at YSC Sports in Wayne. Fortunately for the Union, the workout was indoors. The team will train there this week before leaving the winter weather for Florida, where they will train for three weeks in Orlando.
The season opens March 19 in Houston against the Dynamo.
Last week, Nowak says the addition of Valdes should increase competition and not be seen as a negative toward Califf. After Monday's workout, Califf gave his take on the situation.
"When they bring somebody in who plays your position, that competitiveness comes out in you," said Califf, who turns 31 on March 17. "For the growth and betterment of the team, we have to try and bring in the best group of guys, and so far Carlos has done a good job and fit in really well."
Califf says he is curious to see how Nowak chooses to align his defense.
"It will be interesting to see what the coaching staff has in line for Michael, who can play right, left or center back or in the midfield," Califf said.
Califf, who earned $250,000 last year according to MLS Players Association information, has a guaranteed contract for this season.
In addition, Orozco Fiscal and midfielder Roger Torres were on loan to the Union last year from their club teams, and deals have to be made this season for their permanent rights.
Both players were working out Monday, but deals have yet to be finalized, according to a team official.
Assuming everything gets worked out, the Union will have a pleasant problem of fitting in at least five experienced defenders for four spots.
Then again, the Union and all MLS teams will need more depth. The schedule expands from 30 to 34 games this season.
"We were pretty fortunate with injuries last year and didn't have many, especially in the back," Califf said. "We will need a little more of that depth."
Contact staff writer Marc Narducci at 856-779-3225 or mnarducci@phillynews.com.
