Yes, cpu sliders and player sliders have no effect over a game when started with the controller positioned in the middle.
No, you only need 1 controller to successfully get the sliders to work. It has nothing to do with 2 controllers making both teams play correctly. The game plays correctly with just 1 profile regardless of what other people want to think. There is another theory that if you start the game with the controller on a certain team, that team will only benefit from the user sliders. Absolute ridiculous accusation. I'm seeing generally the same play style for both teams under this discovery.
The initial reason I wanted to employ a 2nd controller was because I was afraid after several games started with the controller placed on a certain team, that team would win every game. This has since been disproved. I've seen 3 out of my last 7 games won at home with the controller on the away side at the start.
So, the idea you'll want to use is to set up the sliders the way you want the game to play, and then start the game with a controller on a team. Doesn't matter which one either. Once the ball has been kicked off, switch it to the middle and the cpu vs cpu is now forced to accept your personal sliders for both cpu skill and player skill.
This method tricks the computer into thinking that a human is playing and has to account for the sliders. There is a difference in the AI when you play it physically when it comes to sliders. You can change things while playing and literally see it take effect. If you start a game with just the controller in the middle of the team select and make it spectate as the menu say's, you can change the sliders to your hearts content and I personally guarantee you that the cpu will not acknowledge your adjustments. You may think it did 1 game out of 7 or 8 but I personally guarantee you that more often than not, the cpu plays its own style of game when left on spectate.
If you're like me and have a vendetta against interceptions, reduce the interception slider to 0 as part of your profile slider settings. I have seen 9 interceptions total in 17 games. Only 1 game had 2 interceptions in it.
Do this, make that profile just as I suggested. use the sliders you want but definitely reduce interceptions to 0. Leave pass reaction and pass rush at 50. Don't reduce pass accuracy or increase it. Don't decrease and increase pass catching. Play a game with this method where the controller is on a team at the start and the switch it after the ball has been kicked and in mid air. I promise you, interceptions will be all but non-existent. I'm not saying they shouldn't be in the game, I just set out to see if I targeted just those, if I could make a difference with my theory and it actually worked for once. I'll eventually find where the sweet spot is to get interceptions but at least I know I solved the initial problem.
After you watch that game. Don't select a team and let the controller be in the middle at the start of the game and I promise you it will be an interception fest 3 out of 5 games. Bet on it!
Also, make sure you're testing all of your games in franchise. Not play now.
One last thought, my version is for literally owning because owner have nothing to do with how games are played out on the field. they improve the team but do not coach them. If you want to dig in deeper and be a owner/wannabe coach, (which defeats the purpose of watching/owning IMO) either coach it physically or have fun setting up 32 coaching game plans and garbage like that, prohibiting the cpu teams from using their own logic.
I know this is a lot but hopefully this helps.