I wouldn't say the impact of experience is that small, but 10% is very low if you look at the difficulty to get a player experience above average.
And it's hard to actually prove it, it was more about observation and impressions I had.. As an example I looked pretty deeply at, I had two centers who were really similar,
(2522997) on season 15 and
(11802129) on season 14, Rojas was a 13-10-12 and Ranieli was a 14-11-13, their driving and handling were practically the same. The league average centers got much better on season 15 and my team didn't change at all, then if you look at their numbers, Rojas got around 25% more points, even though he shot a lot more, and about 5% more rebounds.
Rojas had prominent experience and Ranieli had pitiful.