Sean Gilbert, who is trying to unseat DeMaurice Smith as the executive director of the NFL Players Association, said in an open letter that Smith may eventually cost the players $10 billion.

Gilbert, a former Pro Bowl defensive tackle, said Smith’s decision to agree to the current Collective Bargaining Agreement at the end of the 2011 lockout will cost the players a cumulative $10 billion by the time the CBA has expired.

Gilbert said the players erred by hiring Smith, who is a lawyer and not a football player. Gilbert portrays Smith as being out-maneuvered by NFL commissioner Roger Goodell, taking money out of the players’ pockets in the process.

“We have already seen a shift of $2.5 billion from the players to the owners in the first four years of that deal and it will grow to $10 billion by the time this 10-year deal expires,” Gilbert wrote in an open letter circulated Wednesday.

“We have a $10 billion problem from the 2011 CBA. I believe it can be attributed to DeMaurice Smith’s lack of institutional football knowledge. Smith is a lawyer. He is a litigator, not a businessman. He has no background in football.

“Gene Upshaw was not a lawyer. He was a former player. During Upshaw’s time leading the union, the salary cap increased every year. When the NFLPA hired a litigator with no institutional football knowledge, the cap went down for three straight years. Since Smith took over, owners didn’t just roll back the cap. They slashed it.”

Three years ago, it was smooth sailing for Smith when he unanimously won re-election with no competition for his job.

At least four contenders for the position will attempt to convince the 32 player reps that they can do a better job leading the union.

NFLPA president Eric Winston has communicated the platforms of the quartet to all the reps, each of whom had to receive nominations from three player reps to get on the ballot.

Gilbert, who has been very public in his opposition to Smith, promises to file a collusion case against the league, wants the 2011 collective bargaining agreement drastically changed and also favors an 18-game schedule, something a large majority of the players have been against.

The other three current candidates are Detroit-area attorney James Acho, sports and labor attorney Andrew Smith and former Navy Admiral John Stufflebeem.

There has also been speculation that attorney David Cornwell might throw his hat in the ring, but he hasn’t commented. DeMaurice Smith won out over Cornwell and former players Troy Vincent and Trace Armstrong when he first was elected in 2009. Any other candidates must submit their player-rep support by March 5, 10 days before the election at the union annual meeting in Hawaii.