Fantasy baseball is a marathon, not a sprint. Yet every league has that owner who panics way too much, way too soon. Don't be that person. Beat that person.
Despite their star-level track records, the following five players struggled a great deal during Week 1 of the fantasy season. If you can trade for them on a discount, act now before someone else does.
Zack Greinke, SP
Two subpar starts (both against excellent hitting teams -- the Rockies and Cubs) aren't enough to think Greinke doesn't have it anymore, all of a sudden at 32 years old. As a mitigating factor: The new D-back made his season debut pitching with the flu. Greinke is still striking out a batter per inning, so the stuff is there, if not the results. While it's fair to expect his numbers to drop somewhat, since he'll be pitching half his games at Chase Field instead of the pitchers' paradise that is Dodger Stadium, his career ERA at Chase Field prior to 2016 was 3.34. This season, Greinke's ERA is 9.90, but his FIP is 6.31. That's obviously poor, too, but it's an indicator that he really hasn't been as bad as his numbers suggest.

Troy Tulowitzki, SS
Don't be shocked by this slow start, as Tulowitzki was hit on his right knuckles on March 23. However, there are no issues with ligaments or muscles -- woes with a greater likelihood to linger and affect performance. This is a bruise, something that figures to go away shortly. Tulo has a low batting average largely because of a .133 BABIP. There's only one place for that to go. And with baseball's recent influx of star-level young shortstops, this veteran does not have the name appeal that he once trumpeted. All the more reason to acquire Tulowitzki as a buy-low option.

Matt Harvey, SP
The talk all spring was that Harvey was "back." Not that he wasn't good last season -- he certainly was (2.71 ERA) -- but that this year, his second season removed from Tommy John surgery, he'd return to his 2013 form, when he was arguably the best pitcher in the game (2.27 ERA). Harvey showed off a great slider throughout Spring Training, and his velocity was solid. Then he ran into some health issues that had nothing to do with his arm, and his preparation for the season was altered. Harvey pitched two innings in his final tuneup before Opening Day, then pitched three days later. Then, he didn't make his second regular-season start until a full week later. Not surprisingly, Harvey has struggled out of the gate, going 0-2 with a 4.63 ERA. But wise fantasy owners will note his unlucky .333 BABIP and the fact that he has allowed only one extra-base hit so far. The right-hander should get into rhythm pitching every five days going forward, and his numbers will improve. Now is the perfect time to target Harvey, with all the positive attention being handed to his 100-mph-throwing teammate, Noah Syndergaard.

Randal Grichuk, OF
Grichuk's season K rate (44.4 percent) to date is extremely high, but such is more of a "real baseball issue" than a problem in fantasy, where feast-or-famine hitters can still hold value. Looking ahead long-term, he will need to struggle for a while to lose playing opportunities to someone such as Jeremy Hazelbaker, St. Louis' 28-year-old rookie. As long as Grichuk remains an everyday player, fantasy owners will want to hold onto him for his power (17 homers in 350 plate appearances last year). It will show up sooner rather than later.
Todd Frazier, 3B
Yes, Frazier is hitting just .167, but he has historically performed at his best before the All-Star break (.271 average, 65 homers; .239 average, 45 homers in the second half). Don't be surprised to see him turn it on soon, when his unsustainably low .118 BABIP regresses toward the mean. The reigning Home Run Derby champion has just two walks in 26 trips to the plate, a sign that he is anxious on his new team. Still, Frazier remains a terrific player with the ability to belt 25 to 30 long balls this year.