1. Good players do not gear their alts up through old tier/current tier raiding anymore, as much as before. They do it through LFR and Valor.
Because of this, you see a lot less alt run pugs than before created by good people.
2. Because of the shared lockouts you do not see anymore 25 man raiders making 10 man pugs all the time. Also, whilst more unusual, you do not see 10 man guilds doing 25 man pugs. That was not as common, but on my realm there used to be atleast 5-6 10 man goes 25 man pugs each week.