Google Maps
estimates driving time from the Hertz lot to Dodger Stadium as one to two hours if you leave any time between 4:30 and 5:00 PM. (Google doesn't have an HOV-lane option, which seems like something they should add.) The other major rental agencies are nearby. It takes at least half an hour to get through baggage claim and the shuttle, maybe more if you rent from a discount agency and the shuttle hits traffic.
So I'd say it's possible but unlikely that you'll arrive in time for the first pitch, but you probably won't miss more than the first inning or so.