Tahm Kench's Win Rate by Games Played

Someone posted a thread highlighting how low his win rate is upon release, but they failed to point out how much his win rate goes up with games played. For support, he's currently hovering at 38.74%, and players with only 1-5 matches experience are even lower at 37.57%. Jump to 5-15 and you go up about 6% to 44.88%. 15-50? 56.05%, nearly 20% higher than the win rate of the 1-5 folks. Only 12.32% have played 15-50, admittedly, so the numbers might be a tad skewed by that. However, I expect it'll hold true, as the leap from 1-5 to 5-15 remained after more people worked their way into that category.

So, to what do you attribute this spike in win rate? Every champion has a learning curve, and everyone tends to get better with experience, but he's the simplest champion Riot's released in forever, so I can't imagine why players new to him would be messing up that badly. Could it be that he's so unique that many need to suss out how to play him in the most effective manner first? In the normal matches I've played, I've found through trial and error that acting as babysitter to my ADC (and the rest of my team) tends to be the best way of going about things with Tahm. It's only normals, yet I'm 7-4 with a 3.76 KDA and have only been outplayed by another Tahm once (in a match where our ADC was AFK for 15 minutes and yet I still finished 2/8/15 [74% C/Kill]). The funny thing is I'm still learning and improving.

I just can't see that process accounting for so huge a gap in win rate, though. What do you guys and girls think?