Perhaps experimenting is the wrong word maybe tinkering would be more apt. But I do think that there has been an experimental element to the extent that he has been willing to roll the dice on a few rookies who have shown great potential over players who haven't quite been at there best but at least you know what you're getting.
Case in point is probably Koroibete over Speight. Koroibete offers more than Speight in attack right now and his defence is tremendous but how he was going to perform at test level was still relatively unknown whereas you knew what Speight would give you.
There is some logic to what Cheika is doing if only people would look beyond the idea that if they think something should happen then the coach should agree with them. I don't agree with everything that Cheika's done but there is some logic to it. While he is trying to win as much as he can at the moment he is also, in his mind, preparing for 2019.
Firstly, he has discarded some players who he believes will not be up to it in 2019. Higgers, Fardy, Cooper and Moore are examples of this thinking, with Moore being handled differently because of his iconic status in the team.
Secondly he has promoted some very young players who are not yet ready for test rugby but he has promoted them anyway. I think he is doing this to try them in the furnace now hoping it will pay off in 2019. Think Uelese, Robertson, Hanigan, Rodda, Tui, Dempsey, Koroibete. (If you watch some of Koroibete's defensive positioning in the last game it was cringeworthy but if he can learn that in the fire of test rugby he will replace Speight). Now I don't agree with Cheika that Dempsey and Hanigan in particular are ready for test rugby and I believe they need a pre-season in the gym to bulk up and build core strength; but I think I understand what he is trying to do.
Thirdly I suspect (based on his comments) that Cheika wants badly to try out Hunt at 12, with Beale and Foley as dual fullbacks and Koroibete the other winger. That would relegate Hodge to the bench where he covers a multitude of positions and allows a 6:2 bench selection for some games. Cheika likes 6:2 and often used it in the 2013/14 Waratahs. This game upcoming would be ideal, but Hunt's not recovered yet. I doubt he'll try it for the third Bledisloe, except maybe for 10 minutes off the bench. But I think he'll try it on the EOYT. That being said, Cheika makes some courageous decisions (and some of those courageous decisions are in the Sir Humphrey Appleby definition of courageous - ie totally foolhardy). But certainly not all.
PS: BH81 gets a lot of unfair stick for supporting Cheika's decisions when all he is really doing is trying to explain what Cheika's thinking seems to be. He and I often disagree with Cheika's choices but we can see that Cheika has a strategy he is following and is not the loony tune that some on here think.