I thought it was pretty obvious that in any offensive tactics your team tries to find the player that. the offense is meant to score. If you got to low flow then they will take bad shots at the end of the shot clock.
And just because you chose to play a offense it doesn't mean you'll win with it or that it will work well. Some offenses actually needs adaptation of your team for it to work well
The other thing that I think needs to be taken into account is that a lot of inside shots normally are passes from teammates to players who are in or moving into a good scoring position. In the isolation, they're not looking for a guy who is open and in a good shooting position; they are looking for a specific player and he may not be anywhere near a prime shooting position. No matter how nice his IS may be, if he's getting the ball 18 feet away from the basket, he'll need to beat his man off the dribble to get to use that IS.
I think if there's a "flaw" here it's that the inside player was unable to create his own shot at an effective enough rate for this game. I suppose if instead of passing the ball up, the isolated player jacked up a bunch of contested 15 footers instead, it might have looked more like anticipated. The few times I've run isolation I actually was expecting the isolated player to get more assists because he wasn't a great driver, but had quite nice passing for a big man.