Once again, we see how a silly lack of follow up communication (a very simple thing) has unnerved a buyer.
I think the buyer's concern is warranted. Most likely, the seller may have already shipped and neglected to tell the buyer (which is both stupid and inconsiderate.) Since the buyer was smart and paid via PP (hopefully not as a gift) and used his cc besides, if the seller can't prove delivery, the buyer will be refunded.
OP, you say the seller has good refs, that is in your favor. I'm not understanding why he can't take a few seconds and email you the shipping info.
If a few more days go by and no word and no racket, file a did not receive PP claim (or a PP dispute at least) and PP will contact him and ask him to prove delivery within 10 days. You are covered so don't sweat it. If the seller flakes, you have recourse.
As far as a reference, if the racket shows up and is okay, I would leave something like the racket was as described but shipping was somewhat slow and communication was bad/no tracking number was provided despite inquiries.
This is a similar scenario:
The no box excuse
is sort of lame IMHO. Worst case, some bubble pack, one or two two plastic garbage bags and some tape will get it there. Or, take the racket to one of the many shipping stores and let them handle it. Walmart sells boxes. I am not aware of a box shortage.
Let us know how it works out.