I think their plan was for Frenchy to take the young guys under his wing and be a leader. Working out great! Hosmer's been following Frenchy's lead all season!
You can be a leader, and a clubhouse guy as fourth outfielder. If that's all they wanted out of Frenchy, they could have gotten it. Also, not worried about Hosmer other than the fact that he is a powerful young hitter who most likely doesn't benefit from the "Sietzer way."
Sietzer's approach is great for slap hitters and guys with no power like Escobar but imo can ruin guys like Hoz, Gordon, Butler, if they buy in, and those are the type of guys you build your team around. You want those guys to be patient enough to select the pitch they want and then drive it, and keep being selective until a 2-strike count in the pitchers favor. At that point you want them fouling pitches off until they get the one they want.
It sounds easier said than done, but if you look at the great offensive teams that is how they handle it. A great player example would be Kevin Youkilis.