Baltimore Orioles: Some of these are easier than others. The O's have a quality bullpen, a dangerous lineup, a superb defense and one of the game's best managers. That leaves exactly one hole.
Baltimore's rotation ranks 14th in the American League in ERA. Meanwhile, the O's bullpen has worked one of the heaviest loads in the AL, thanks in part to the starters' ineffectiveness.
The Orioles do have a variety of options, and it appears that Wei-Yin Chen will be back from injury soon. But they need more innings and quality than their rotation is currently delivering.
It may not be an ace -- after all, there aren't many of those -- but a legitimate No. 2-or-3 type of starter could be a major difference-maker for a team that overall may be even stronger than it was last year.
Detroit Tigers: The truth is, the Tigers are very likely to make the postseason regardless of whether they do anything before the Trade Deadline. They hold a four-game lead in the AL Central and have a run differential that tells the true story: they're easily the best team in their division.
With that said, they could definitely get stronger. And the easiest fix would be in the bullpen, where the Tigers have sought stability all year. Jose Valverde wasn't the answer in the ninth, and so there's upheaval again.
The good news for Detroit is that there's nothing easier to fix in-season than a bullpen. Just ask the past two World Series champions. The 2012 Giants and '11 Cardinals both experienced ninth-inning turnover during the season, and the '11 Cardinals made over virtually their entire bullpen at mid-year.
It can be done, and it has been done. And if the Tigers want to go deep in October again, they need to do it. They need at least one reliable late-inning reliever.
New York Yankees: There are few spots where the Yankees wouldn't benefit from a bat, truth be told. Their offense, dragged down by a barrage of injuries, has just about run aground after a hot start.
Two spots in particular stand out: outfield and catcher. The Yanks have an army of outfielders, but only Brett Gardner is healthy and really counts as an everyday-caliber player. A corner outfielder who can get on base, hit for power and play regularly could be a huge difference-maker.
There's another spot, though, that might be just as valuable. The Yankees let Russell Martin leave during the offseason and never really replaced him. There aren't a lot of catchers out there who can hit, but if one became available, it would be an enormous upgrade for New York.
Pittsburgh Pirates: Like the Yankees, the Pirates need a bat and have several places where they could plug one in. They could certainly use a right fielder. But the greatest upgrade that Pittsburgh could make would be at shortstop.
Clint Barmes, still a quality defender, has seen his offense drop to the point where the Bucs simply can't play him regularly anymore. Jordy Mercer is an adequate hitter, but no more.
Much as with the Yankees and catchers, the problem is that two-way shortstops are incredibly valuable commodities and they rarely become available. But if one were to come on the market, the Pirates need to pounce. They have a chance this year, but they need to upgrade their lineup without sacrificing too much defense.
San Diego Padres: The conventional wisdom has long been that the Padres can pitch, but they can't hit. This year, that notion is flat wrong.
San Diego actually has quite a nice offense, especially adjusting for its pitcher-friendly ballpark. Instead, it's starved for quality starting pitching.
Edinson Volquez and Clayton Richard have struggled mightily. Eric Stults and Jason Marquis both have the kind of peripheral stats that suggest sudden, swift falls from their current perches.
The Friars rank second-to-last in the National League in starters' ERA, which is simply stunning considering where they play their home games. The NL West is very much there to be won, and the Padres shouldn't ignore the opportunity. They need to get rotation help.