Yes, Styx and....Toy???

Here, enjoy!  

The most obvious example was The Blackjacks opening for Fish in DC. I think they were a local band who got an opening slot at the last minute (the ticket didn't mention an opening act at all). They described their act as an "old school rock vibe" that basically amounted to safe contemporary "punk-rock" with barre-chords instead of power chords. I don't remember a single song or melody. I do remember the band looking really nervous and relieved when it was all over. I don't think anyone even approached their merch table.

The other was In My Diary Of Need, opening for the Flower Kings in New York at the Highline Ballroom. These guys were actually on the ticket, but not listed on TFK's website or elsewhere. I think there was a small part of the audience who was there just to see them(who proceeded to heckle and throw stereotypical slurs at TFK during their set)  Whereas the Blackjack's where just incredibly bland, these guys were obnoxiously bad. Some kind of weird blend of Jane's Addiction and screamo. At the end of their set they had some kind of bongo duet with the strobe lights going, which gave me a nice headache, and I couldn't wait for them to get it over with. (Thankfully TFK were awesome that night and more than made up for it).

Point being, I think this may be a similar circumstance with Toy, where it's a decision made with booking agencies/management rather than the band themselves. Sometimes this results in a hilarious mismatch of audiences. The small part of the audience paying a premium just to see Toy will probably feel incredibly out of place when Yes come on. Likewise, you probably won't see many people in Roger Dean shirts approaching Toy's merch table. Doesn't really benefit any of the acts involved in any positive way, but like I said, many times these decisions are made without the artists consent or involvement.