This early in the season, it's difficult to say anything definitive about a baseball player, especially a batter. Every stat is subject to the dreaded "small sample size" caveat; too many crazy things can happen in a single week or two of games.
Remember Tuffy Rhodes? He hit three home runs for the Cubs off Dwight Gooden on Opening Day in 1994 -- then went on to hit just 10 more home runs the remainder of his Major League Baseball career. Pitcher Justin Masterson struck out 10 Blue Jays hitters on Opening Day in 2012 en route to an eight-inning, one-run effort, -- then posted an ERA of more than five the rest of the way. History is littered with the crumpled-up baseball cards of fast-starting rabbits who couldn't even come close to maintaining their pace.
When it comes to what's real from the early going, we know we should not look at home runs or batting average or RBIs. We know, yet we look anyway, because what else can we look at?
The good news is that the math has been done. Eric Seidman at FanGraphs found that the quickest statistics to become reliable are swing and contact rates. That's because these are judged by the pitch instead of the plate appearance, and by now most regular position players have already seen more than 100 pitches. There are close to four pitches per average plate appearance, so those per-pitch numbers are coming at four times the rate as the plate appearance statistics.
So swing rate it is! That's something we can look at. Generally, swinging less means being more selective, and that's usually a good thing. So let's look at players who are swinging less this year compared to last year. Their added selectivity should be good for them.