It's been about a month that the Mets have been without Jason Bay.

If you remember, Bay collided with the Dodger Stadium outfield wall on July 23. He did play two games after that, but reported symptoms of a concussion on the team's flight from Los Angeles to New York.

Dave Lennon reports that the Mets will not let Bay participate in significant physical activity unless he's headache-free for 48 hours.

The Mets are being extremely careful with Bay, who signed as a free agent in the winter. Check out assistant general manager John Ricco's comments in the Lennon piece.

The Mets, of course, have a very notable recent history with head injuries. Two seasons ago, Ryan Church suffered two concussions in 11 weeks and was lost for the season because of head trauma. Last season David Wright suffered a concussion after getting clocked by a Matt Cain fastball.

The Bay story has even more relevance this week after a study, published in the Journal of Neuropathy and Experimental Neurology, links concussions to ALS, or Lou Gehrig's disease. In fact, researchers at Boston University suggest that Gehrig's disease may have resulted from repeated concussions or head trauma.

Lennon writes that at this point the Mets might just be better off letting Bay sit out the remainder of the season. With this week's news and the Mets' history with concussions, the Mets might be best served by playing it safe.