Why you shouldn't go "standard" 21-9-0 on ADC's anymore

So, with the defensive mastery rework, there was a change made that rendered the "standard" 21-9-0 on an ADC 100% obsolete.

Typically you would go 2 into Block, 2 into Recovery, 1 into Unyielding, 3 into Veteran's Scars, and 1 into Juggernaut.

However, with the new defensive mastery page, I personally feel like 2 into Block, 2 into Swiftness, 1 into Unyielding, 3 into Veteran's Scars, and 1 into Tenacious.

My reason for this is because, you're an ADC, you don't build too many defensive stats, so you're going to utilize a ton of the slow reduction and tenacity. Not to even start on how you only get 1 extra point early game from taking Juggernaut, unless you get a Randuin's for whatever reason.

With that said, let me know what you guys think, or if this is something you've already been trying.