Confession: I don't care about spring training statistics. I don't care that Bryce Harper is hitting .214, and don't care about Erasmo Ramirez's 1.14 ERA. There are a few reasons for my apathy. Evaluating players based on 50 at-bats is silly, the competition in spring is generally weak and some players work on things that can impact their performance. 

At the same time, I have to admit that my opening statement is not 100 percent true. While I don't care about stats like batting average and ERA, I do pay attention to some things during spring training. Here's a list of things that may get me to reconsider the value of some players before the start of the regular season. 

  • Playing time battles - It sounds obvious, but an easy way for a player to produce is by getting playing time. Knowing that Conor Gillaspie is going to open the year as the White Sox starter at third won't help much in Fantasy leagues, but it does let you know that you shouldn't draft Matt Davidson just yet. You might want to draft Yordano Ventura, though.
  • Pitcher velocity - I've done some research on the topic, and pitchers who gain speed on their fastball tend to experience breakouts. It's one of the reasons Tyler Skaggs has become more appealing to me late in drafts. Drew Hutchison is another player who has received some strong velocity reports from beat writers, but he hasn't pitched in a park with PITCHf/x yet this spring. We'll have a much better idea of who is throwing harder once the regular season begins, so be on the lookout for that.
  • Pitchers throwing a new pitch - This one is tricky, as they rarely tend to work out. Still, I find myself fascinated with guys who add new pitches. The problem is, pitchers may scrap the pitch by the time the regular season rolls around. The offering may also be terrible, which isn't going to help their performance. Martin Perez added a cutter, and Jake Odorizzi has worked with Alex Cobb on a splitter. Both have late appeal depending on the size of your league. Thankfully, Al Melchior is keeping a comprehensive database this spring, so see if any player tickles your fancy.
  • Context, context, context - This partially goes against my opening statement, but hear me out. If a player is performing well, find out if there's a reason for it. In Skaggs' case, the Angels were able to get him to switch back to his old mechanics, which has helped his velocity return. If you can find a significant change in a player's approach, you might be able to justify pushing up your board slightly. 
  • Post-hype sleepers - Jason Vargas posted a 2.14 ERA this spring, does that mean you should hurry up and grab him in your fantasy league? No, because we know what Vargas is at this point. The equation changes when you start talking about a young, promising guy. Or, in this case, a player once thought to be promising. This works for both Drew Hutchison and Mike Olt. Both players were once regarded as prospects, but fell off the map for some reason. Strong springs have given them roles with their clubs, and there's a chance they can perform in a full-time role. 
The key to all of this is not overreacting. With known players, you shouldn't really be moving them up or down your board. Harper is probably going to be fine once the season starts, and you don't want to be the dope who passed on him based on 42 at-bats. In the case of a guy like Hutchison, you're allowed to bump him from "undraftable" status to "late round flyer" status. What you don't want to do is jump all over Hutchison in the 13th round of a draft because he had a nice spring.
Show some restraint, and you'll be just fine. Quote batting averages, and you'll have a bad time.