As the trading deadline approaches, teams are open to any and all moves that might make them better. Some clubs have sought upgrades at positions where they've already received decent production, but the higher the bar the trade target has to clear, the fewer the potential fixes (and the higher the price). The path of least resistance for a contender hoping to improve is often to patch a particularly weak position with an average player who can give it more than it has been getting without costing too much in any other area.
The weakest performance by a collection of players at any position on a contending team this season has been at second base in Detroit, where seven players -- notably Ramon Santiago, Ryan Raburn and Danny Worth -- have played at replacement level or below, combining for a total of -2.2 WARP. It's no coincidence that the Detroit Tigers traded for a second baseman on Tuesday, filling what had been a gaping hole with Omar Infante, who should be at least average for them the rest of the way. We can see the same pattern on display in other acquisitions: The Dodgers traded for Hanley Ramirez because their shortstops -- notably the injured Dee Gordon -- had combined for -0.6 WARP.
Although some positional holes have already been plugged, several more remain. The teams that manage to find fixes for their most obvious flaws might be the ones that emerge from the pack of contenders with a playoff berth. The following are the most glaring positional weaknesses that contenders are still trying to fill, as well as potential fits for each team.