Right now would he be a sub? For whatever reason, Morata just hasn't worked out that well for them since he joined and Giroud, despite getting the starts, still feels like the super-sub he doesn't want to be.
There is a genuine opening for a striker to go there and start and that situation doesn't come up all that often at a top six club.
I still don't think it will happen as he just doesn't feel like a Chelsea signing but if it the chance came, as long as they paid our asking price, I wouldn't blame him for moving. I'd be disappointed but it's something we have to accept will happen when players do well.