You could put it something like this:

"Ok guys, if we want to go further down this road, we have to be honest and take a hard look at our strengths and weaknesses. You all have contributed a lot to our group, and we need to get more focused. Where's your comfort zones? ..... Here's some of the feedback I'm getting from our listeners....."

The Beatles fired Peter Best and changed to Richard Starkey. They were able to make these type of decisions.