It was pretty close really, it was probably a strike. It was definitely an argument out of frustration for having just struck out. He got tossed INSTANTLY, he turned around, made a face, and then got ejected.
He was bumping up against the ump and everything, Ortiz had to restrain him, and Francona came out basically trying to get ejected, he looked somewhat heated too. I feel bad for the umps that they constantly have to take this kind of crap, but its nice to see that Renteria actually cares enough to argue a call and get ejected. We need passion on the team dammit!