If you are anything like me as a fantasy baseball manager then your lineup and rotation is constantly updating. Finding the latest bargain players on the waiver wire and riding the hot streak for a few weeks until the fire burns out is one of my favorite things to do.
Trading is just as fun, or at least trading a player with great numbers during the most recent stretch of play. Championship teams are built on guys we buy low and sell high and there are plenty of those players out there right now.
J.J Hardy, Baltimore Orioles- It has been two years since Hardy was relevant in any league, but now he has ridden a month long hot streak and has resurfaced, however, don't expect him to remain there. His May numbers (2 HRs, 10 RBIs, .247) are closer to what you'll get the rest of the way than the 9 HRs, 18 RBIs and .370 average he put up in June. He is typically a better hitter in the first half of the season so his best days are most likely behind him. The shortstop market is shallow, but I would take a guy like Stephen Drew (20 point jump in average after AS break without loss of power) or Yunel Escobar for the remainder of the season instead of Hardy.
Ryan Roberts, Arizona Diamondbacks- Roberts has never played more than 110 games in his career as a utility man and his career high in home runs is 10. It is unlikely that at age 30 he is going to keep up his 20 HR/24 SB pace. If anything the steals might keep coming, but the power won't. There a few third baseman (Danny Valencia, Chase Headley) out there who will give you equal, if not better production from this point on and you could still get something for Roberts if you dealt him now.
Brennan Boesch, Detroit Tigers- Boesch's 12 HRs, 40 RBIs and .310 average look very attractive right now, but on this day in 2010 he had 12 HRs, 45 RBIs and a .345 average. He went on to finish 2010 with 14 HRs, 67 RBIs and a .256 average. The numbers speak for themselves, start looking for someone to replace Boesch immediately. His career high in home runs in the minor leagues was 28 at double-A, so his track record suggests he won't face plant quite like he did in 2010, but don't expect him to keep up the average or run production. You might be able to pull in a hitter like Ichiro Suzuki, Andre Eithier, or Mike Stanton in a deal for Boesch.
Adam Dunn, Chicago White Sox- Dunn is hitting .171 with just 8 home runs (Yikes! For a second I though I was reading Matt Stairs batting line). Dunn has been bad this year, but nothing that a little post-All-Star break streak can't fix. Dunn hit 40 or more dingers for five straight years before slumping a bit in '09 and '10 by hitting 39 in those years. He's a home run hitter and home run hitters don't all of a sudden forget how to hit because they are in an AL lineup. With some time off in July because of the All-Star game he will obviously not be playing in, he will regain his stroke and finish the season on pace for his usual 40 homers. That may only amount to 17 or so from this point on, but I'd take a strong second half from Dunn over Todd Helton, Billy Butler or Aubrey Huff or whoever it is you are starting at first base.
Nick Markakis, Baltimore Orioles- This might be too late, but Markakis has been raking recently. Since being a season low .204 at the end of April, his batting average has climbed back to .296. That makes sense because he is a career .297 hitter. He also has 7 steals in 2001, a number that is better than his total each of the past two years and he might swipe nearly 20 bases by year's end. He hasn't hit 20 or more home runs since 2008 and he might not do that this year, but only because his first half wasn't to par. If you make a trade for Markakis now you won't get the 23 homers or 112 RBIs he racked up in 2007, but you will get the same hitter. I'd expect between 10-12 homers and 50-55 RBIs from Markakis the rest of the way. That is better than what you will probably get from Melky Cabrera or Matt Joyce.
Rajai Davis, Toronto Blue Jays- Davis is notorious for being a cheap steal option, but this year he is even cheaper. His .237 batting average is well below his career average of .274, but since his average after the All-Star break is .308 he's a near lock to imrpove. He will swipe bags like he always has and when his average improves he'll reach base more often so he'll have more chances to reach 50 steals for the second year in a row.