"Bullpens are the most delicate of baseball ecosystems. Remove one piece – any piece – and you run the risk of having a whole season collapse like a tower from Jenga, the wood-block building game.

And, in the event a team reaches the playoffs, the bullpen's role becomes more magnified than any other aspect of the roster.

Which is why the big news for the Rangers on Saturday was not the result in a lackluster 5-0 loss to Oakland, but the results of an MRI exam on reliever Frank Francisco . The exam revealed inflammation in the latissimus dorsi muscle, the broad back muscle that extends to the side and is responsible for extension. Francisco was placed on the 15-day disabled list, and there is no real timetable for when he might start throwing again. Translation: no time soon.

Another translation, courtesy of manager Ron Washington: "I said it earlier this year and I'll say it again now: We can't be what we want to be without Frankie. We need him."

Do they ever.

The hard truth of the matter is that although the Rangers' bullpen has been good this season, good isn't good enough in the postseason. To wit: the Rangers began the day with the third-best relief ERA (3.31) in the AL, but it was only third among the four teams that started the day holding playoff spots.

Relief ERA barely begins to tell the story of how sustainable a bullpen may be.

Save percentage indicates how well they can close out a game. The Rangers rank third of the four playoff teams ahead of only Minnesota. The Twins went out and traded for Los Angeles Angels closer Brian Fuentes on Friday to address that need.

The percentage of inherited runners allowed to score indicates how well a bullpen can clean up somebody else's mess. The Rangers rank last in that category.

Innings pitched paints a picture of just how fatigued a bullpen may be come playoff time. The Rangers have the most innings – by far – among the playoff leaders. They upped their total to 391 1/3 with 4 2/3 innings of relief after Rich Harden faltered Saturday.

That is why the Rangers so badly need a healthy Francisco should they make the playoffs. They can't further diminish the bullpen. Despite a 3.76 ERA, Francisco has been dependable in the eighth inning. Since moving into that role three appearances into the year, he's compiled a 2.84 ERA, held hitters to a .220 average and has 57 strikeouts in 50 innings. "