The Eagles began spring workouts on Monday, and while Tim Tebow was at the NovaCare Complex after he signed a one-year contract, the team was without Evan Mathis, Mychal Kendricks and Chris Polk.

Mathis, who has been the subject of trade speculation and has it made it clear that he wants a new contract, stayed away from the start of workouts and isn't expected to participate any time soon, an NFL source said.

The workouts are voluntary, but the left guard was in attendance last year even though he was unsatisfied with his contract situation then and was also on the trading block. The Eagles did not offer specifics, but the majority of players on the roster were expected to be present this week.

Kendricks' absence, nonetheless, was a surprise. He had a scheduled trip to Costa Rica, according to a source close to the situation, and plans to eventually attend workouts. But the timing of his vacation was conspicuous.

The linebacker also has been mentioned in trade rumors, but they may not have as much weight as the Mathis reports. The Eagles traded for Kiko Alonso and extended DeMeco Ryans' contract this offseason, giving them three starting-caliber inside linebackers along with Kendricks. Coach Chip Kelly has said that he wanted to improve the depth at the position.

Kendricks is entering the final year of his four-year rookie contract.

The Eagles tendered a contract to Polk, a restricted free agent, last month, but the running back has yet to sign an offer sheet that would pay him $1.6 million next season. He, too, could be seeking a trade. The Eagles added DeMarco Murry and Ryan Mathews to a running back group that includes Darren Sproles.

Mathis' long-term plans for spring practices were not known. He is under no obligation to attend the gatherings that will take place over the next several weeks and morph into organized team activities - more formal practices with coaching - in late May.

But every player is required to attend mandatory minicamp on June 16-18. If Mathis were to skip minicamp, he could send a message to the Eagles that he also plans to hold out from training camp in July.

Mathis signed a five-year, $25.5 million contract in March 2012. He is slated to make $5.5 million in base salary this season. When Mathis approached the Eagles about a new deal in February 2014, the team granted his agent, Drew Rosenhaus, permission to seek a trade.

Kelly confirmed last month that Rosenhaus had the same freedom but that the Eagles weren't actively shopping Mathis. Rosenhaus was at the NFL meetings in Phoenix looking for a partner, but it may prove difficult to move the 33-year-old lineman, especially since the Eagles aren't likely to give him away for little in return.

Asked if he expected Mathis to be on the team at the start of the 2015 season, Kelly said, "I hope so."

A 10-year veteran, Mathis has arguably been the Eagles' most consistent offensive lineman over the last four seasons. He was voted to the Pro Bowl the last two years and was a first team all-pro in 2013. He missed seven games last season with a knee sprain, but when he returned for the second half he seemed to pick up where he left off.

The Eagles are light on the line after releasing Todd Herremans in February. They have yet to sign an offensive lineman in free agency. Kelly said that Allen Barbre would replace Herremans at right guard.

But Kelly does not have an obvious replacement on the roster if Mathis were to leave. Reserves Matt Tobin and Andrew Gardner struggled last season. Kelly, of course, could expend a high draft pick on a lineman. He may already have plans to supplement an aging group that includes 33-year-old left tackle Jason Peters.

It is unlikely the Eagles would flat-out release Mathis, although he could force their hand if he holds out through training camp.

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