The A’s, the Astros, the Angels and the Rangers. You probably think of them as enemies. But what if, this year, they are closer to allies?  Not in the sense that the Mariners want to see them succeed, but in that they are so mediocre, they can almost be considered friends.  Seattle (18-20), after all, has not been good. Nearly a quarter of the way into the season, the club has fallen well short of expectations after taking Toronto to seven games in last year’s ALCS. But the M’s don’t have to be great to take the AL West Division. Just good. And based on what they did during this week’s series against the Braves, there’s enough of that good to get them into the postseason.  I know that looks like whirlpool-level spin for a team many thought would be competing for the best record in the American League at this point.…