By Ridge Mahoney

From his comments Wednesday in a telephone conference call with reporters can be gleaned that Union coach Peter Nowak is not done tinkering.

The waiving of right back Christian Arrieta Tuesday revamped the roster yet again; he’s the fourth 2010 starter to be jettisoned, along with forward Alejandro Moreno, midfielder Fred and goalie Brad Knighton.

"The roster of course is not set,” Nowak said from the team’s training camp in Orlando, Fla. "The roster compliance deadline is March 1, and we have to make a decision at the end of this camp. The roster is not in place yet - we still are working on some things that could improve our roster offensive and defensively.”

Rumors that the Union had signed Colombian winger Jorge Perlaza turned out to be false; he’s in the Portland camp though he’s yet to sign a contract. Earlier this week Nowak acknowledged the Union needs more attacking punch to counteract opponents blanketing forwards Sebastien Le Toux (14 goals and 11 assists last year) and Danny Mwanga (seven goals as a rookie); during the conference call he didn’t respond to questions that the Union is trying to sign Colombian forward Tressor Moreno.

The most significant offseason moves to date are designed to strengthen the spine of the team: holding midfielder Brian Carroll and the Colombian duo of center back Carlos Valdes and veteran goalkeeper Faryd Mondragon. Carroll, 29, has played on championship teams for D.C. United (2004) and Columbus (2008); the foreign newcomers are expected to upgrade two more of the team’s problem areas during its expansion season (8-15-7, 35 goals scored, 49 conceded).

“He is such a great guy and everyone is looking up to him,” Nowak said of Mondragon, who is 39 and played in the 1998 World Cup. “Even with his experience, you wouldn’t know it because he puts everything on the line and he’s not looking for any free passes in training.

“He’s just a joy to work with every single day. He enjoys coming to practice and he puts extra work in after practice. As a coach, it’s a dream to work with such guys.”

Valdes, 25, is bringing a toughness and consistency that U.S. veterans Danny Califf and Michael Orozco Fiscal didn’t often provide last year. That pairing grew stronger as the season unfolded, but the league and Philly have yet to either extend Orozco Fiscal’s loan deal or convert it into a transfer.

Nowak’s affinity for blood-and-guts warriors, no matter what sport they play, is well-known. During the conference call he compared Valdes in appearance and ferocity to one of the NFL’s best linebackers, Ray Lewis of the Baltimore Ravens.

“Carlos Valdes is doing very good,” said Nowak. “He speaks English, so he can listen to what we are telling him and he is understanding the tactical part. He is strong and for the last two weeks we have been bringing him along with the group and he is learning. He is an excellent professional and when he plays in the middle, he doesn’t like to let anything or anybody get through.”

Philly tied the U.S. U-17 team, 1-1, in its first preseason match Monday. It plays the University of South Florida Thursday.