In Series 1, the show centred around the Garrisons, but featured enough of the other characters too. Matt Garrison was the natural leader of the band. He was basically the everyman character. He was the one who didn't get involved in the silliness of the other boys (Wooing Woo was incredibly OOC, Series 1 Matt would have stayed out of it), and he was the one who kept the band together.
Then they brought in Jake Somers.
I don't think Jake was a terrible character, but his addition to the show changed the dynamics too much. Sure, the band might have needed a second guitarist at times, but other than that, he wasn't needed as a permanent member. He came in and suddenly it wasn't about the Garrison family anymore, but about Jake. Matt goes from being the nice-but-assertive one to becoming Richie Cunningham to Jake's Fonz. Even though he was still the lead singer and nominal frontman of the band, Matt was constantly in Jake's shadow. Rather than being the natural leader of his own band, he was now intimidated by Jake.
I really don't blame Brentley Gore for bowing out after Series 2. If you look at the character of Mark Winkle, that's what would have happened to Matt and the actor saw that, and I'm glad he got to go before his character was completely wrecked.
The makeup of the band was just ridiculous once the Garrisons were written out. Jenny and Tiffani both had very different voices. I don't think Jenny could ever truly have been replaced, and while I liked the character of Sam, her voice was too similar to Tiffani's. She lacked the strength and depth of Jenny's vocals and it all became quite samey. Try to imagine her singing Castles on Quicksand or This Time... Do you see what I mean?
Replacing Matt with Mark was the single most pointless addition to the show (yes, even more pointless than Lorena). Matt was lead male vocalist and lead guitarist. So to replace Matt, they would need another lead male vocalist/guitarist. Except we now have Sam on keys and Jake on guitar and lead male vocals... and Mark on keys and backing vocals... except they didn't need another keyboard player, nor another male vocalist. He was redundant in the band. There was no point to him at all.
Also, I don't like the way Tony was sidelined in favour of Mark. There was the episode where he wrote a song for Sam, and it was still "Jake" singing it, even though we know Tony is a competent singer. They could have put Mark to use and put him on drums while Tony took the mic, as there was at least one episode where we see Mark on drums.
The problem with writing out the Garrisons is that the show then became nothing more than another high school sitcom. To me, Jake would have worked better as a solo act. There could have been a friendly rivalry between him and the Dreams, and sometimes they could even have roped him in when they needed a second guitarist.
The thing I disliked about Jake becoming the leader of the band is how he ruled by dominance, unlike Matt, who led because he was well liked and respected by the other band members. Jake was an outright bully to Sly, and while you might argue that Sly could be a jerk, he honestly wasn't that bad and he did have a conscience, even if he was fond of fighting it! Most of the time, he did mean well. You had characters walking on eggshells around Jake and that's not the sign of a good leader. I think Jake would have worked much better if Jenny had stuck around. She would have given as good as she got and kept him in check. They also made a much better couple than Jake and Tiffani.
Yeah, that relationship. At first, it seemed sweet: the tough guy and the ditzy surfer girl, but as the series went on, I didn't like the coupling at all. Tiffani seemed to lose her perky and fun personality, and while you would expect her to mellow out and mature a bit as she got older, I think a lot of it was down to Jake. It was too intense and for me, it just seemed a bit too OTT, and it made Tiffani fade.
At the end of Series 1, I actually thought Matt and Tiffani would be end-game (he did seem to like blondes!). There were several hints througout Series 1, but that's for another post!
We can only dream.