A basic primer or refresher on defense is always a good subject.
A plus play occurs when a player makes an exceptional play where a normal contemporary at the position can not make. A minus play of course is just the opposite. In all reality for the purposes here, a plus play takes away a hit while a minus play gives up a hit. An error occurs when a player bobbles, fumbles, boots, drops, makes a bad throw..etc.
Now for the fun part is the ratings. The position assignment chart shows the big league averages for each player position. They say average, I say bull, more like minimums. Range is normally the determining factor for making plus plays. Glove determines the catching part while the arm takes care of the throwing of course.
A rule here most accept is range over glove. The reason is if a player has a high range, the glove can be a little on the weak side as things will even out between plus plays and errors.
Arm needs to be minimums in both categories or preferably better for SS and 3B. Outfield arms can be on the weak side a little as missing the cutoff man is not an error. However, if they must make a play at the plate they tend to be offline quite a bit.
Catchers get their own little paragraph. A high glove stops the passed ball and limits errors. Range is helpful in the wild pitch area with bad control pitchers and getting to bunts. A good arm slows down the stolen base attempts. Pitch calling helps the pitchers pitches.
Another factor we figured out in defense is the Fielding Instructor. He needs to have a strategy and discipline rating over 50 (truthfully over 60 in both) to be helpful to players along with the high glove rating. I always like a high patience rating also to teach the minor league position players.
One thing to remember is that all players will make an error, the object is to limit the amount of mistakes the best you can. Discovering a defensive problem is not always a cut and dry proposition either. Looking over the Team and Player Statistics carefully will generally reveal the problem, fixing it could be tough however.