According to mmajunkie.com:

This past weekend's "Strikeforce St. Louis: Heavy Artillery" event, which featured the long-awaited return of heavyweight champion Alistair Overeem to the U.S., drew an average of 308,000 viewers on Showtime.

A two-and-a-half hour special, "UFC's Ultimate Fights," which aired on Spike TV to counter-program the Strikeforce event, drew 894,000 viewers.

Showtime is available in approximately 12 million homes. Spike TV is available in 98.6 million homes.

Compared to Strikeforce's most-recent Showtime-broadcast event, January's "Strikeforce: Miami," the numbers were down 40.43 percent from the 517,000 viewers that tuned in to see a pair of title wins by Nick Diaz and Cristiane "Cyborg" Santos along with performances by Bobby Lashley and Herschel Walker.

[UPDATE] by Michael Rome: This is close to their average number for non-Gina/Herschel shows. Considering the main event and what went into this card, the numbers are more than acceptable.

HT: SSreporters