A Quick Note on AP Ezreal with Runeglaive

TL;DR: AP Ezreal's win rate is 7% higher with Runeglaive. Ranger's or Stalker's seems to be the more optimal choices than Skirmisher's (2% difference) for Ezreal's Smite.

Patch 5.12 introduced a new jungle item - Runeglaive - which has the interesting effect of improving AP Ezreal dramatically. I found ~10k games with mid lane AP Ezreal in Platinum-Diamond level NA ranked solo queue and found the following:

Playstyle	# of Games	# of Wins	Win Rate
No Smite	681	282	40.29%
Smite + Runeglaive	9654	4571	47.35%
Smite + No Runeglaive	86	27	31.40%

A simple two-sided proportions test of (No Smite) vs (Smite + Runeglaive) gives the p-value at 0.003062, which suggests the result is statistically significant despite the relatively tiny sample for No Smite.

Out of the players who did build Runeglaive, their choice for Smite is as follows:

Smite Choice	# of Games	Popularity	Win Rate
Ranger	3043	31.54%	48.04%
Stalker	2249	23.31%	48.33%
Skirmisher	4357	45.15%	46.36%

It seems that Skirmisher's does not perform as well as Stalker's or Ranger's (46% vs 48%); but Skirmisher's is definitely the more popular choice. Poacher's was used for less than ten games; the interested reader may attempt to compute the number of Poacher's bought using the data above. 

It's not surprising that AP Ezreal is doing a lot better with Runeglaive. Runeglaive gives AP Ezreal an AOE spell that can hit minions, thus vastly improving his waveclear - his traditional weakness. But it is quite amusing to see how a single item can dramatically change a champion from obscurity to LCS limelight.

Note:

1. The lane choice for the Ezreal player is determined using Riot's data.

2. The detection of AP Ezreal (as opposed to AD Ezreal) is by the proportions of magic and physical damage dealt to champions.