In between trade talks and early negotiations with free agents on Wednesday, baseball general managers considered some wide-ranging changes that include changed roster limits for September and protective headgear for pitchers.    They discussed altering the longtime rule allowing active rosters to expand from 25 to 40 from Sept. 1 through the rest of the regular season. Some teams have been reluctant to use the larger limit late in the season.

General managers have cited not wanting to disrupt minor league teams in their playoffs, and those decisions have led to big league games in which teams have differing numbers of available players.

"Each team should have equal number of players available every day," said Joe Torre, MLB's executive vice-president for baseball operations. "I just think you play the whole season with one set of rules and the most important time of the year, especially for clubs that are in a pennant race, I just don't think it's fair for it to be done [with a] different number of roster people."

Torre said one possibility would be setting a fixed number of players who must be on the active roster for September games.

"We've talked about 28. We've talked about 30," he said. "It was talked about at length today."

The players' union would have to approve the change.

"This was a subject in bargaining in 2011, but no agreement was reached," union head Michael Weiner said. "If MLB has a midterm proposal to make, we will consider it. This clearly is a mandatory subject."

Cap liner

General managers also went over ways to protect pitchers from injuries after two were hit on the head by line drives late in the season. MLB staff have said a cap liner with Kevlar, the high-impact material used by military, law enforcement and NFL players for body armour, is among the ideas under consideration.

"If we settle on something that is going to make sense, and obviously the pitcher has to be comfortable with it, we'll obviously put that in as soon as possible," Torre explained.

Oakland's Brandon McCarthy was hit on the head by a line drive in September, causing a skull fracture and brain contusion that required surgery. Detroit's Doug Fister was hit on the head by a liner off the bat of San Francisco's Gregor Blanco during the World Series. Fister was unhurt and stayed in the game.

MLB medical director Dr. Gary Green is to give a report at next month's winter meetings in Nashville, Tenn. MLB senior vice-president Dan Halem has said protective headgear for pitchers could be in place in the minor leagues for next season.

On the trade front, Arizona GM Kevin Towers said he'd listen to trade offers for two-time all-star right-fielder Justin Upton but thought a swap was not likely. And Texas GM Jon Daniels said the Rangers remained interested in re-signing all-star slugger Josh Hamilton.

Daniels hopes Texas remains a fit for Hamilton, a slugger who appears likely to leave after helping the team win American League pennants in 2009 and '10.

"I think there's this perception that we don't want Josh back. That's not accurate. I'd love to have Josh back. It's got to work for both sides," Daniels said. "Whether he ends up here or not, I feel like some need to defend him right now that everyone's kind of throwing out the negatives with him.

‘The reality is like this guy's been a stud for this franchise for the last five years and done some things that have enabled us to reach levels we hadn't previously reached."