This is why you trade Brad Penny.

You trade him because you have the depth to compete without him. Clay Buchholz, in a one-night stint Friday with the Boston Red Sox, reminded everyone that he's more than ready to pitch for Boston every fifth day.

He showed us that his 7-2 record with Pawtucket is no fluke, and that his 2.36 ERA (second- best in the International League) transfers favorably to the next level.

His line against the Blue Jays was not spectacular (5 2/3 innings, 4 hits, 1 run) but it was good enough to win the game. And good enough to fire up the trade Penny talk again.

You don't trade Penny because of one bad outing. That outing was a rarity – he's pitched very well for Boston this season. Saturday marked just the second time in the last 11 starts that Penny had given up more than three earned runs. 

The only real criticism has been Penny's inability to go deep into a game. He hasn't thrown seven innings in a game yet this season, the longest such stretch in the major leagues. He hasn't even gone six innings in six of the last 10 starts. He has just one win in his last nine starts dating to May 30. He's left the game in the hands of the bullpen far too often.

You trade Penny because it would be a coup for the front office.

The Red Sox signed Penny for $5 million during the off-season. It's a one-year contract; he won't be back in a Sox uniform in 2010. So why not turn him into an asset that can help you in the future? They've got Buchholz under their control for another four seasons, and it seems clear he can be a serviceable fifth starter or better.

Trading Penny for a young player that can help the Sox now or in the future is the equivalent of getting something for nothing.

Boston signed Penny off the injury scrap heap, and has an opportunity to use him to bring in an asset that will stay with the organization in the future.

Thanks for the half-season. Good luck in the National League.

There are plenty of teams starved for pitching. Just ask the world champion Philadelphia Phillies, who have Pedro Martinez coming out of semi-retirement to join the team.

Teams around the game are lining up for a shot at Roy Halladay, and why not? He's quite possibly the best pitcher in the game, and stands to be the biggest name available before the July 31 trade deadline. 

Contenders like Philadelphia, St. Louis, and (of course) the New York teams are said to be cobbling together packages of prospects to acquire Halladay.

If any of them gets him, it will instantly make them a formidable playoff favorite.

And what of the teams that don't get Halladay? Penny would make a fine consolation plan.

Teams that lose out in the Halladay sweepstakes may be willing to swap some of their young talent to Boston for a power pitcher with a proven track record of playoff success.

Could Penny help the Red Sox if he stays? Absolutely. Could the Red Sox withstand losing Penny? Yes.

That's why they should make the move, even though Penny has pitched well in his short time in Boston.

Tom Caron is the studio host for Red Sox broadcasts on the New England Sports Network. His column appears in the Press Herald on Tuesdays.