In Strat-O-Matic defense is involved in the ratio of 30/216. Thus about 1 outcome of the dice in every seven rolls will be determined by your defense.
The 30 defensive chances are broken down as follows:
C 3
1B 2
2B 6
SS 7
3B 3
CF 3
LF 2
RF 2
P 2
The catcher's arm is more important than his defensive (range) number which is the least important of all the positions in Strat.
OF arms are very important, particularly in pitcher's parks where less runs are scored and an extra base means more.
Clearly it pays to concentrate your defensive efforts up the middle.
You can do fine with one 4 in the outfield. Luzinski for example has worked well for me. He has a decent error rating and arm which attenuate the negative effects of his range.
I personally always use 1's at SS unless I get Banks or Pesky.
At 2nd base the only non-1 I use is Hornsby.
A big advantage to 1' s in the infield is increased double play opportunities.
One of the teams I posted earlier in the thread has a middle infield of Pesky and Hornsby. Their offense compensated for the defense.
I never use a 3 in CF. I tried Hack Wilson twice. His offensive stats were good but the teams stank.
Hope that helps inform your choices of players.