If Sony abandoned Killzone for Horizon, that's a hint that it flopped.
If Sony closes Evolution Studios after they released DriveClub, that's also a hint that the game flopped.
I don't know about Knack sales but it was a shitty game as seen by reviews at the time.
None of these games flopped, they all sold well enough, perhaps not to heightened expectations, but they did well.... Killzone and Knack were the more successful of the lot, remember, they were launch games, so they moved units by default. As a matter of fact, the game I bought with my PS4 was Shadowfall, it's the only disc game I have, since I'm totally digital this gen. I still remember all the gifs of knack out-selling a popular Nintendo game which came out at the time "on this here forums", You might want to revisit some old threads, as Knack did very well.
1886 was successful too. Maybe DC was the least successful, but the weather patch brought lots of folk on, the re-reviews helped and the great support it received in dlc, bikes expansion + the season pass got many folk to buy the game+season pass, due to the the great word of mouth and added content it received. In the end, DC was definitely successful, but it was too little to late for EVO, since their last two launches were not smooth ones, with reports of lots of wastage and underperformance from the higher brass at EVO. Sony just felt they should cut them off for many reasons than just DC...
Even what was left of EVO, after Sony got rid of the old guard, they couldn't catch a break, maybe something creeped into their DNA along the way, because On-Rush failed when they went to Codemasters. People wanted a traditional Racer or at least a mode that represented traditional racing and they expected more content at launch, after trying the beta, Onrush lost lots of potential sales.... because the messaging for what it was was not quite clear and people were looking for podium finishes and the like....
It is what it is, but sometimes you just have to do what you have to do for the bottom line, and Sony felt they had to let EVO go under the circumstances. I have to say, Evo's games are fun, their tech is amazing. Even On-rush is a very beautiful looking game with great IQ and tech and of course lots of fun, but they needed to hit their messaging better, they should have traditional podium finishes in there day 1 and with more content. EVO just needed to nail their launches better, so maybe they had a fundamental management issue after all...
As for your assertions on if these games were really successful, it's not quite right. If Playground abandons Forza Horizon for a bit and focus on Fable, does it mean Horizon 4 flopped? Should Naughty Dog only make Uncharted because the sales are great? Then we'd never get Tlou. Killzone series was successful on PS3 and so was Shadow fall, but if Guerilla did not try something else, we would never have received the magnificent Horizon Zero Dawn. It's good to give a series a break or shift it to another team or even reboot it, to keep things fresh or change it up......
FYI, From the rumor mill.......Guerrilla is working on an MP style Killzone. They have two teams btw and San Diego is rumored to be working on a new Uncharted. This means that Naughty is already working on something new for PS5 after they wrap up Tlou2 soonish, as they have two teams just the same. The UC team should be working on something new as we speak.....
You see, you don't need to buy a million studios. You can expand on the ones that you have, split them. You keep the great talent pool, they share tech and help each other out on their projects. You shift talent and resources on a project as you see fit....That's s why you can have two franchises coming out of ND, perhaps 3 soon, if they expand again. All the games will look great, perform great and younger directors can get guidance from the seasoned UC and Lou directors. You need to read the market, you need to see how things can evolve beyond saying "we bought five studios" on an E3 stage.....
