First of all that original link is to an old column from 2000. That’s the bad news. The good news is that Kerry did in fact think that Yost played for the BoSox. Here’s an item from an earlier column by Gammons:

These people deserve a Camden Yards for putting up with narrow aisles, seats built for scrawny 10-year-olds, no room to buy concessions and the grunge of an outdated facility that last year wasn’t properly cleaned, per choice of those who look down from the luxury suites. It’s not going to happen, though, not with a trust owning the team or the local political delegation. There are no Tip O’Neills or Bill Welds, just city councilors who suggest using Braves Field (which hasn’t existed for 30 years), and national representation summed up by a junior senator whose idea of the common man is someone who can only put $10,000 into his campaign funds, thinks low-cost housing is a $680,000 house on Nantucket, changed his middle name to be J.F.K., threw someone else’s medals into the ocean in a Vietnam Veterans rally and out-Hillaried that lifelong Yankee fan by appearing on WEEI’s Eddie Andelman’s show and told listeners he’s a lifelong Red Sox fan whose favorite Bosox player was Eddie Yost (too bad Yost never played for the Red Sox).

Note: Thanks to Ben Domenech of Red State for the help.