Sorry, but 195 lb Kovacs would get destroyed at LB. Making reads from the safety position is much easier than making reads from the MLB position. If you haven't practiced at MLB and your 195 lbs your going to get pulled in the wrong direction and put in the wrong spots (worse than Ezeh) and then get bull dozed even further from the ball by a Guard of Center. Plugging in safeties at LB doesn't just automatically work.
Also, the 4-2-5 would probably hurt us against the run. For all the complaining about all this stuff we actually aren't bad against the run. Having only two LBs being able to pursue (it's much more difficult to pursue as a down lineman as you already have a O-lineman on top of you) would hurt us against the run. I agree on passing downs a 4-2-5 would be better, and maybe mix it in a little on other downs, but we can't just turn over the whole thing right now.