Overall is not a very good way to assess the quality of your team; it overemphasizes certain ratings that aren't that important (especially, very high stamina and durability in pitchers who are bad enough that you don't want them to be able to pitch 240 innings).
Your team is only OK. Your current record understates the quality of your team somewhat, but .500 is about where I'd expect you to end up, maybe a little worse than that.
To improve the team going forward in future offseasons:
1) As has been said before, you need a CF something terrible.
2) Get a legitimately excellent bat at DH.
3) The pitching staff lacks top-end arms, although you do have 5 ML-caliber SP, they're 4 SP3s and an SP5. If you got 2 genuinely good pitchers to replace your marginal back-end guys, especially in the bullpen, the staff would be in much better shape.