The Orioles and Mariners played a game last week, and it went 18 innings.

An 18-inning game, of course, is a rare occurrence, but it can happen at any point in a season. But within that game, the Orioles and Mariners used a combined 48 players -- 23 for the O's, 25 for the M's.

This is the kind of thing you'll only see in September, when roster limits are expanded to 40 and teams generally have an ample number of bench bats and bullpen arms on hand.

This is all well and good, except for one little thing:

September is the most important month of the season.

The O's, of course, were -- and are -- vying for the playoffs, and one can't help but wonder if that 18-inning game, which Baltimore wound up winning, might have had a different outcome had the usual 25-man roster limits been intact. Even if Baltimore had won with 25 men, one wonders how that marathon win would have affected its arms assemblage the rest of the week or month.

This is not to pick on the Orioles, because manager Buck Showalter was, naturally, well within his right to use any and all bodies available to him. But it does present a point that sticks in the craw of many a front-office and managerial type this time of year. For baseball is the only major sport that has different roster rules in its most pivotal month than it does at any other point in its calendar.

"If you're a club that, for whatever reason, doesn't bring up as many players as other teams do," said Braves general manager Frank Wren, "there could be some mechanism that creates an equal playing field, just as we have the other five months of the season. I think there's more growing consensus in that area."

Consensus enough to work out a change for 2013? That's a possibility, if recent discussions among members of Commissioner Bud Selig's committee for on-field issues are any indication.

The topic actually seemed to be gaining steam ahead of last winter's newly negotiated collective bargaining agreement, but eventually was lost in the wake of the many more pressing matters being discussed at the time.

Now, with the importance of September all the more amplified by the expanded postseason format and the increased incentive to win a division outright, the roster situation is once again a trending topic. It appears possible that some consensus on September rosters could be reached over the winter and negotiated with the players' union.

Any fan of fairness has to hope that an agreement is reached soon, because the current construction leads to some awkward alignments. Teams are allowed to add as few or as many September callups as they wish, expanding their rosters up to as many as 40 players. Some teams call up fewer than others for a variety of reasons, be it for payroll concerns or providing opportunity for prospects, or as a result of the number of worthwhile prospects in the upper levels of their systems.

To illustrate the point: When the Yankees faced the Twins on Tuesday night, they had 36 players on their active roster; the Twins had 31.

Some players from contending clubs gripe that the September arrivals can alter clubhouse chemistry or consistency. But the players' union will always support the notion of these callups because it creates Major League jobs at season's end.

What would make sense, however, is a limit on the number of players a team can employ on a given day. The number typically tossed around in regard to this idea is 30. When managers exchange lineup cards, they would each designate the 30 players available for that game (or, alternately, for that series).

"It makes all the sense in the world," Tigers general manager Dave Dombrowski said at last year's GM Meetings.

And to prevent teams from stacking their roster with relievers and not listing their resting starting pitchers as "available," the recommended rule would be that the 25-man roster from Aug. 31 stays intact for the remainder of the season, thereby allowing teams to filter five callups in and out of the active alignment on any given day. This rule would, however, have to account for injuries or shutdowns that take place within September. In those situations, a locked-in roster spot ought to be opened up for another player.

"I think there could be a lot of strategy to it," said Brewers GM Doug Melvin, a longtime proponent of changes to the September roster situation. "I think it's important, just for the integrity of the game. We could have a play-in game for the playoffs, and the two teams could have five players' difference."

Because out-of-contention clubs usually use September as an evaluation period for their young talent, Melvin proposes that active roster limits only apply to games in which one or both of the teams involved is still, mathematically, in contention.

"If two teams are mathematically eliminated," he said, "so be it."

The main issue obviously revolves around how the expanded rosters affect the races. And there are also questions about how the rosters ought to work for the newly initiated Wild Card round of the playoffs.

As it stands, the Wild Card game will retain the same rules as the other postseason rounds, in that each team will submit a 25-man roster ahead of time. Unlike the other rounds, however, this "round" consists of a single game, so the incentive exists for teams to stack their bullpens and only list one starting pitcher. So these postseason games could wind up resembling September games, when managers are more prone to quick bullpen hooks and pinch-runners than they are at any other point in the season.

That, too, is a matter that doesn't sit particularly well with some executives, and it could be another issue that receives attention in the winter. Because now that the late-season schedule has been given increased importance with a new postseason format, it's time to give its roster rules a tweak.