This is very true, young guys are to be taken with a grain of salt, until they are proven they can be consistent. Beckham for example has had two very good half seasons, and one horrible one. At this point in time, what does that make him. The same goes for several guys on my team. Prime example is Brett Gardner. But then again, players that have shown a long term decline such as Travis Hafner, Lance Berkman, etc are thriving despite the fact that many people thought they were done.
The problem is, early in the year, when a guy goes on a cold streak it is more apparent in his stats because of the small sample size. But, I also think that skills eventually win out over the long haul. And you can't fight the law of averages either. Carl Crawford could play in the grand canyon and not hit .200 for the year. Hanley Ramirez will not hit under the mendoza line for the year. Ryan Roberts will not be more valuable than Dan Uggla. The Twins will not have the flu the entire season. Just things you can hang your hat on.