User blog comment:Krankenheimer/Critical Strikes/@comment-16737371-20140416201947/@comment-1330314-20140418060502

This is the other thing: changing crit from a percent chance to a percent AA amplifier does not change damage output. Here's the proof:

1% chance to critically strike means that, on average, every 1 autoattack out of 100 will deal double damage. This is the definition of a percentage chance. What this also means is that your autoattack-based DPS is 99*1 (the number of autoattacks that don't crit) + 1*2 (the autoattack that crits) = per autoattack on average.

Now let's turn this 1% chance to critically strike into 1% extra damage per autoattack. Over the course of every autoattack, each AA deals 1.01 times your AD, therefore your DPS over the course of 100 AAs is 100*1.01 = per autoattack. You deal exactly the same damage whether crit is a percentage chance or a damage amplifier, so non-random autoattack enhancers wouldn't increase your damage output.

You mention a "constant damage increase", but that also makes little sense: while it's true that champions with crit would deal more damage on most autoattacks, they'd deal far less damage than a crit, and would never be able to inflict the damage spike of a crit unless they build 100% of this new stat. Moreover, to deal the same damage as a crit these champions would have to apply this damage over the course of several autoattacks, whereas a champion with crit would be able to deal double damage in one lucky AA. This nerfs the random burst potential of marksmen and makes them completely DPS-focused, so if anything it would be better for squishies and tanks alike (marksmen too, since they get far more reliable damage output).

On the issue of marksmen dealing too much damage against squishies, I really don't think it has anything to do with crit. Marksmen are suppsed to deal massive damage in the late game, so if you're dying to them too quickly chances are you either got caught and/or focused (if you're a back line mage), went in before the tank could draw fire (if you're an assassin) or simply did not build enough health or armor (if you're going for a build like full AD Riven or the like). If marksmen wouldn't be able to kill anyone they targeted in the late game, there would be no point in having them in a team comp.

If there is an issue, though, it is with, and not the "many other things" you fail to mention: LW is an item designed to counter armor stacking, i.e. tanks and bruisers, but currently it works as a strong damage amp against everyone, including squishies. The armor penetration you're meant to build to deal more damage against squishies is flat armor pen, but Last Whisper penetrates even more armor than a, which has the highest amount of flat pen, against even the squishiest targets: bar , the champion with the least armor at level 18 is , with 66 armor. Because Last Whisper penetrates 35% of the target's armor, it penetrates 23.1 armor on her, 3.1 more than Youmuu's. Effectively, it's too good against the champions it's meant to be weakest against. Changing the effect to, say, 50% bonus armor penetration would provide similar amounts of armor pen on tanks and bruisers, higher amounts against heavy armor stacking and far less penetration against squishies, which would solve your problem. If you don't believe me, there's math that can prove it.