I agree with the above posts. I'll add a couple of thoughts:

Building a team for Pure Baseball requires the same set of balancing acts that you need to build an MLB team. My experience is that, just like in MLB, you can never have too much pitching. Teams with great 1-3 starters and awesome bullpens will (1) always be in the race and (2) fare very well in the playoffs (subject to the vagaries of small sample size, of course).

So, following the principles in the previous posts to evaluate individual players, you should try to get vary solid starting pitching, anchored by at least one (better 2) ace(s), and then get the hitting to support them. In looking at hitters, I focus on getting young, proven position players who don't necessarily have the gaudiest stats. The moneyball principles apply in PB as they do in MLB -- OBP and SLG are what score you runs.

Another tip - there are ALWAYS decent to very good relief pitchers available in the annual drafts. With the exception of the true relief aces, there is huge year to year variation in the pitchers that will post huge seasons (e.g. Cormier and Hasegawa last year), both of whom will be available in many Free Agent pools this year.