PEORIA, Ariz. -- Scratch one name off the Padres' long list of candidates for the Opening Day rotation.

Right-hander Cesar Vargas was optioned to Triple-A El Paso on Monday, one of four roster moves announced by San Diego. Vargas -- who missed the final four months of last season with a flexor strain in his pitching elbow -- would not have received the necessary workload had he remained with the big league club.

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"What he came off last year, with the depth of competition we have in the starters race, it gets down to the point where there weren't going to be innings for him to be stretched out in camp," said Padres manager Andy Green. "Now that he feels healthy, it's, 'Go pitch. Go pitch in the Minor Leagues, get your way back here.'"

Dinelson Lamet , Aroni Nina and Michael Kelly were also reassigned to Minor League camp. Lamet had an outside chance to crack the bullpen, but none of those moves come as a surprise.

The Vargas decision certainly qualifies, however. He sustained his elbow injury last May during a start in Arizona in which he allowed seven runs in 1 2/3 innings. Before that, however, Vargas had posted a 3.34 ERA while showcasing immense poise and a devastating cutter. He made two appearances this spring, allowing two runs (one earned) over 3 1/3 frames.

San Diego's rationale for sending Vargas to the Minors certainly makes sense. Jered Weaver , Clayton Richard and Jhoulys Chacin are all rotation favorites. After that, approximately six others will compete for the final two spots.

"The race is getting whittled down," Green said. "As you go through camp, you start looking at nine guys in a starting mix. We, frankly, don't have innings. As much as you'd love to go all the way through camp and give guys a legitimate chance to compete, you can't get your guys ready for the season. So you have to start making decisions."

Vargas was the first casualty, leaving Luis Perdomo , Jarred Cosart , Trevor Cahill , Christian Friedrich , Tyrell Jenkins and Paul Clemens fighting for two spots. The Padres also have a few bullpen spots up for grabs, and a few of the pitchers mentioned above are candidates.

Green added that he expects to see Vargas back with the big league club in the near future.

"He missed [four months] last year," Green said. "He wasn't ready to compete full bore with everybody else. He was just a step behind. I'm glad he feels great, and I would, at some point in time during the season, consider him a depth starter."

With the moves, San Diego has 64 players in Major League camp.

AJ Cassavell covers the Padres for MLB.com. Follow him on Twitter @ajcassavell.