Buy low on Russell Westbrook, others

It's never easy to acquire or trade a stud. If you have a big-time fantasy player, you'll find it tough to trade him when he's on fire. If you want a big-time fantasy player, you'll probably have a hard time prying him out of the current owner's hands. That's why it's crucial to be bold and make your move in those small windows of time when the player you have is red-hot, or the player you want is in a lull. Here are five players that fit the bill right now:

Buy low

Kobe Bryant, SG, Los Angeles Lakers: I almost put Kobe in the sell-high section, despite his relatively pedestrian play of late. After all, in a recent interview, Kobe said the reason he hasn't practiced all season is that he has "very little cartilage under my right kneecap; it's almost bone on bone." That's not the news you want to hear about a 32-year-old guard who has 14-plus seasons of wear and tear on his knees. On the other hand, despite playing five fewer minutes per game than last season, he's still cranking out quality stats across the board. Then there's the most important factor: it's Kobe Bryant. Despite his sore knee, he hasn't missed a game this season, and it's clear that the Lakers are limiting his minutes so he'll be healthier as the playoffs approach. That means there's a very good chance that he'll finish the regular season on a high note. Considering that he's ranked 27th during the past month on the Player Rater, Kobe's trade value may be at its lowest point since the '90s. Go get him.

Russell Westbrook, PG, Oklahoma City Thunder: My man-crush on Westbrook is well-documented, so I'm not going to drone on in detail about why I love his fantasy game. Besides, after the monster numbers he put up during the first two months of the season, it's pretty obvious why he can be a prolific fantasy option. But, alas, it's a long NBA campaign and almost all young players have a statistical swoon at some point. Westy is no exception. His production in the past few weeks has been subpar for his breakout season. He's posted double-digit dimes only twice since Dec.12; luckily, one of those was his latest game. Mostly, though, we're feeling the decline in his field goal percentage, which he'd boosted to around 44 percent during the first couple of months. In four January games, he's shooting 38 percent and bottomed out with an eight-point (3-11 FG), two-dime, six-turnover performance on New Year's Day. He's far too good to let this statistical dip last for long. This may be your only chance to land his massive potential at a reasonable price.

Danilo Gallinari, SF/PF, New York Knicks: The sharpshooter's sprained knee is going to keep him on the pine for another week or two. That's bad news if he's on your team. It's great news if he's not, because you should be able to get him in a trade at a reasonably low price. Gallinari's overall production is about the same as last season. However, anyone who drafted him for his 3-point production has to be disappointed with his dip from 2.3 per game last season to 1.9 this season. Toss in the extended absence and 41.6 shooting from the field, and it's hard to imagine an owner who wouldn't be frustrated and willing to trade him. Don't be shy about getting him now if you need treys. I expect to see a solid month of 17 points per game and 2.5 3s per game before the season is over.

Sell high

Derrick Rose, PG, Chicago Bulls: During his first two seasons, Rose was helpful in fantasy but wasn't a difference-maker. If you're like me and get excited about guards who shoot the ball well, then you appreciated that he shot better than 48 percent during that stretch. Combining that with good scoring, dimes and free throw percentage, Rose was capable of contributing to fantasy squads. However, he wasn't one of the better guard options because he averaged just 0.7 steals and 0.8 3-point attempts per game. He's taken on a bigger role for the Bulls this season and it's resulted in a bigger fantasy presence. Rose is averaging 1.1 steals and is hitting 1.6 of his 4.3 3-point attempts per game. Of course, it has come at a price: he's shooting a career-low 45.6 percent from the field and his turnovers have jumped from 2.8 per game last season to 3.6 this campaign. However, since his total volume is up (career highs in shots, free throws, dimes and scoring), those flaws are minor. In fact, during the past month, Rose ranks sixth overall on the Player Rater. While I'm not sure he can remain quite that high, he's certainly capable of finishing the season in the top 10-15. It's always tough to trade a player who is red-hot, but it's the right thing to do because his value can't get much higher. This is especially true if you are running low on steals because his production remains pedestrian.

LaMarcus Aldridge, PF, Portland Trail Blazers: Let me preface this discussion of selling high on Aldridge by saying that the guy is legit. The only reason he didn't post numbers this big earlier in his career is that he had a superstar named Brandon Roy as a teammate. This season, though, the Blazers have turned the show over to Aldridge because Roy's knees have left him out of the picture. That being said, there are a couple of reasons selling him now will get you the most value. The first reason is obvious: he's averaged a massive 27.8 points and 11.6 bounds in his past five games, but he can't possibly maintain that pace for long. For being 6-foot-11, he's been only an average rebounder in his career. In fact, he's never topped 8.0 rebounds but is above that this season. Secondly, he's averaged a whopping 21.2 shots per game during the aforementioned five-game stretch. The Blazers have enough talent that they don't need to lean on him that heavily in the long term; they're just riding his flaming-hot hand right now. There's also the matter of blocked shots. He averaged 1.4 per game in November and 1.5 last month -- the first time he's averaged that many in a month since 2007. As the Blazers lean on him more for scoring, you can expect those numbers to dip back toward 1.0-1.2 per game. It's not a huge knock on Aldridge, but he's not going to be a difference-maker in blocks.

Tom Carpenter is a fantasy basketball analyst for ESPN.com.