While “Cinderella Man’s” $18.6 million bow was softer than expected, it’s still too soon to say which way the picture will go. Of course, Universal hopes that it follows the course of previous summer drama success “Seabiscuit.” But that will take a leggy performance, with the movie falling only moderately next weekend. Last summer’s “The Terminal” is a cautionary reminder of how difficult it can be to bank on a film playing on and on amid the titan titles of summer. Universal says it remains committed and is encouraged by exit polls from opening weekend that showed that word of mouth should be strong. Summer adult dramas have a mixed track record.