I have found a couple things out about doing the stats thing. Hitting, pitching and defense go hand-n-hand together. You can get away with one being weak but the other two has got to make up for it. I split the the stats in hitting to home and away because a team is set up for their home park or should be. Pitching uses ERA and OAV both home and away. I used to do two in defense but that didn't work well and only the overall is needed as it will dictate both home and away, since it isn't broken down to home and away.
Some things I have noticed, a good defense helps pitching more than you would think. The difference between a good defense and a bad one is about a full point in a pitchers ERA and OAV. In simple terms a pitcher that has an ERA of 5.00 it could become a 4.00 (or near it) and an OAV of .300 can easily be .270 or less. Couple that with a good defensive PC catcher and it could be even better. Why is an easy question to answer. One error costs a pitcher about 3.5 to 4.5 pitches or more depending on what happens after. Doesn't sound like much until you start thinking about the back of the rotation guys and the bull pen.
Pitching is sometimes hard to pin point, if ERA and OAV don't match in rank then it is usually because of the defense or the parks being played in. It could be that each player needs to be investigated as to what the cause is.
Hitting is easier, a good home hitting team helps in most instances, at home at least. Being realistic though, you play 81 games at home so if you don't have a .285+ average or better then there is a problem. Your not going to be good if you can't win at home, plain and simple. All the pitching in the world won't help if you don't have the offense there. If a team hits well at home and not on the road then some further thought is needed, and there is an easy but sometimes elusive answer to that.
Most of the hitting and pitching problems are tied to the ball park itself. Close examination of the box scores are needed to figure some of it out. Did the ground ball pitcher give up fly balls? Did the fly ball pitcher give up ground balls? Did the power hitters put it in the air or on the ground? What did the non-power hitters do? It doesn't do much good if a batter went 3 for 5 and you don't know why or as a matter fact 0 for 5.
My interpretation of the hitters stats.
Eye: pitch recognition, type/ball/strike
Splits: effectiveness against pitchers, weak/strong
Power: determines ground ball/fly ball, also if the fly ball can land in stands
My interpretation of pitcher stats.
Stamina: TPC, +15 or +20 for MPC depending on rotation size
Control: pitch location
Splits: effectiveness to hitters
Velocity: strikeouts or inducements
Pitches: how well the pitches are thrown
Notes on this: A low control pitcher can be just as good as a high control pitcher but the splits and pitches are the key and need to be real high. As a batter will chase badly located pitches, though a keen eye and good splits hitter will walk more often. Low velocity pitchers try to get the hitters to hit the ball whether it is in the air or on the ground, a good defense is needed here. High velocity pitchers go for the strike out. The call bull pen and situation determines when a pitcher gets pulled in most cases not just the the TPC, if a pitcher is in fatigue status or not when TPC is met is the key along with auto rest. Also, low split pitchers can be good also, but control and pitches has to be high.