So some background about me: I danced from ages 4-14 in the styles of hip-hop, jazz, tap, ballet, contemporary, and acrobatics. So when I started watching SYTYCD (S2), I immediately fell in love.
The show had my undying love until S6. No, it wasn't the new stage or even Alex Wong getting injured that changed things; it was the fact that there was a Top 6 and not a Top 4, the ONLY TIME there was a top 6 in all seasons. Why? Because the married couple were never partnered with each other and the show wanted to have them do one dance. This was never stated, but it was painfully obvious that the situation had been manipulated for that specific occasion. This paired with the judges' tendency to continuously save their personal favorites even if they couldn't keep up technically and were constantly sent to the bottom by voters made the idea that the show was being manipulated to lead to a certain winner or outcome grow stronger to me.
The series also has an issue with changing its format. The stage change wasn't a huge issue since it was the first time the series had really changed anything since they hired Cat. Soon after though, the show would change its format almost each year: having only a top 10 and all stars, having a top 20 then a top 10 with all stars, having a guy and girl win, and now it's back to just one winner. The constant changes can make long time viewers like myself feel unnerved especially if you're part of the faction that believe the series never needed the changes to begin with.
The saving grace really for me were the strong choreographers and array of styles, however over the years even this has taken a turn for the worst. Compare the styles of dance used in season 2
and season 10
to see that the show has narrowed its scope of dances over the years, giving a HUGE advantage to contemporary and jazz dancers to the point that most winners have been from one of the 2 styles (or ballet which has similar training) with a few exceptions. Many episodes in S10 had two contemp. pieces in a single episode.
With fewer styles showcased, frequent format changes, and rather blatant favoritism and manipulation, I personally stopped watching the show. I'll watch individual performances every now and then, but the whole show as a series has greatly declined.