Thoughts on defense:
D ratings do exactly what they are named for. Unlike hitting and pitching ratings, in which good and bad ones offset and combine. The D ratings are pretty much what you see is what you get.
Range and Arm Strength correlate to plus and minus plays. Glove and Arm Accuracy correlate to errors/fielding percentage.
Look at your team stats and you'll see which positions handle the most fielding chances. That's why so many of us want an SS who goes over the recommendations. The SS has the ball in his hands the most.
In the hypotheticals you gave above, the second SS is better. Great fielder with a good arm. The first is a passable fielder with a great arm. 95 Glove would be extremely rare, not sure I've ever seen it.
The first LF would be better than the second. Reason is that Range/Glove are far more important for outfielders than arms... except for the RF. OFs make most of their plus plays by taking away extra bases, not by outfield assists. And one of our owners has pointed out that in this game, OFs don't make throwing errors. The RF is different because he only handles about two chances per game. Another of our owners theorized that success as an RF correlated far more to the arm than the glove. I wouldn't use that second LF in the outfield, he'd be a first baseman.