Sega doesn't know how to make a good Sonic game for ages, but their other stuff are pretty good actually
Lets talk about SEGA on a global level.
Yakuza is gaining popularity to the point where Yakuza 6 sold on par with Japan. Yakuza 6 has not even sold 1 miliion copies.
Persona, which is not even developed by SEGA, is a key IP.
Sonic? - Global brand power but quality issues.
Bayonetta? - They don't invest in it.
All SEGA's classic IP are auctioned out ( Streets of Rage, Panzer Dragoon, )
What IP's are you talking about?