snip
Well, topos of my: Not that simple.
First of all, penetration tables - and every one of then! - is advisory at best.
Shooting at steel plates of questionable quality - maybe better, maybe worse - could be quite different from actually shooting at a plate on a tank, with slightly different trajectory, different angles (since the ground is not leveled), maybe brand new, maybe has some internal failures, fatigue from previous shots.... bad or good grain sizes, alignement, hardening from bad welding work, fucked up heating.... or the ammunition! Material problems, propellant problems, bore wore out.
So, miriad of dependands.
The biggest anecdotical evidences are these penetration tables. The actual anecdotical evidences, actual combat records are gave you a much better picture. Bad thing, we only now a fraction of the actual damage/penetration occurances and practically none of the non-penetration hits. So much for "real" statistical analisis.
Two more things: split seams means one thing only - the vehicle have to return back for repairs soon. If you imagined a tank falling apart... well, no. However, a second hit could be fatal. (Or not, depends of the ratio of seams failing).
Over 1,5 km you consider a lucky shot. Well, visit some shootig ranges, ask for distances and target sizes. Not lucky. If you see the target.