Trading first baseman Carlos Lee won’t be easy for the Houston Astros. But the restrictions on the team are less severe than they could have been.

Lee, a player with 10 years of major-league service, the last five with the same team, technically has enough service time to block any deal.

However, Lee, made a trade of his own at the time he signed his six-year, $100 million free-agent contract with the Astros in Nov. 2006.

He agreed to waive his 10-and-5 rights in exchange for a full no-trade clause for the first four years and partial no-trade protection in the final two.

Baseball’s labor agreement allows players who sign multi-year contracts before achieving 10-and-5 status to accept such a tradeoff, but only if they get specified partial no-trade protection in return.

Lee, 35, can block deals to 14 teams this season, the final year of his contract, major-league sources say. He also had the right to veto trades to 14 teams last season. Each year, he was required to give the Astros a list of teams to which he would not approve a trade.

The details of Lee’s list are not known, and his $18.5 million salary this season adds to the Astros’ degree of difficulty in trying to trade him.

Then again, the pending long-term agreement between Joey Votto and the Cincinnati Reds will remove one more first baseman from the trade market. Most of the other top first basemen also are signed long-term.

In fact, Lee should have significant incentive to produce this season. His competition in the free-agent market next winter will include only less prominent first basemen – the Dodgers’ James Loney, Nationals’ Adam LaRoche and Giants’ Aubrey Huff, Rays’ Carlos Pena and Indians’ Casey Kotchman.

-Ken Rosenthal