Someone or something had to drive these clients to Buzbee prior to the news breaking. I'm doubting very seriously it was they all happened to click on the same Google AdSense link after searching for "how to sue NFL player for sexual assault."
I don't think this was "ambulance chasing" by Buzbee, though. Buzbee hiring private investigators to seek these women out and get them to sign with him is both criminal (barratry) and unethical, and probably not very smart when targeting someone with the finances to fight back like Watson. That would put his bar card at serious risk.
Eliminating that level of dirty pool, I can think of only two possibilities: either 1) several smaller-time attorneys pieced together that this case had multiple victims, networked, and decided together to refer these cases to Buzbee, or 2) this activity was all reported to one entity (either the Texans directly or someone else who fed it to the Texans). It isn't implausible that the Texans stopped mitigating and guided these women toward Buzbee directly or through a referring attorney once negotiations broke down to where this was their only play.
Got to admit, the sheer balls it would take to keep something like this quiet when the McNairs and Jack Easterby are being drug through the mud daily by the local an national press is astounding, if true.