"90% of all street fights end up on the ground"
Not true. The gracies would like everyone to believe that there are hundreds of thousands of EVIL ex-olympic caliber wrestlers out there who are going to shoot a double on you at the onset of a streetfight.
I've cross trained in bjj, shootwrestling, and am Instructor level in Muay thai. Guess how many times fights have gone to the ground? About twice out of 30 or so street fights.
I've bounced in 5 different nightclubs and the only time I see a fight go to the ground is when two fat idiots get tired and pull each other to the ground.
BJJ is a GREAT art that everyone should train in. However, try using bjj in a packed nightclub or when there are 3 guys who want to kill you and you are alone or with your gf. PUts a totally different paintjob on things.
IMO muay thai is the best followed very closely by BJJ. BUT i'd recommend people train in both.