Do people honestly think there's a team wide philosophical approach? You think Guillermo/Schneider came into camp this year and told them our new philosophy with 2 strikes is to cut down your swing and put the ball in play? or that in general, they all need to spray the ball more to all fields, or increase their contact rate? or with RISP, they all need to do something specific? Do you think ever player would buy into that and change their approach? This isn't little league.
Do you think they sat Springer down and said "I know you've had a f***ton of success throughout your career, but we need you to change this year?". Do you think they've told Vlad to be more aggressive and increase his chase rate?
C'mon. Each individual hitter plays to their strengths. You're not going to have a "complete philosophical overhaul". That said, would a new hitting coach help? It could, but not because he's going to change their approach. If a new coach comes in and they start hitting better with RISP, it's probably a f***ton of luck involved and sometimes you seem to get hitters more dialed in because they know their results cost someone their job. A new coach may also simply provide a new voice to the players and that might have some effect on them, as hitting is 90% mental.
However, the vast majority of these players all have their own personal coach that they turn to when they are in a slump. Someone from their past (dad, uncle, etc.) who got them to the majors - someone they trust - and often someone who just tells them what they want to hear. I already told this, but I know a guy who's a skating coach for the Leafs and he says there are several players who refuse to even skate with him (and refuse to work with other internal coaches). They often don't want to hear the truth. When those players are 'stars', they often have the leverage to make the team fly in their old, trusted coach to help them because they won't listen/work with the team coaches. I 100% expect that s*** happens at in baseball also. If Vlad, Varsho, Kirk and Springer all refuse to work with Guillermo (or any other hitting coach) than there's not much he can do.
Despite our struggles, we're still 7th in MLB in wRC+.