If the post office noted, "that unopened or incomplete ballots have been inappropriately placed in out-going mail bins," it begs an obvious question. Were completed ballots filled out and submitted? Given that they'd look like every other completed ballot, there's no way to know. Could someone have done that? Absolutely. Is there some reason to think that a person stealing ballots wouldn't do that? No. Is it entirely possible that person could have filled out 50 or 100 ballots without ever getting caught? Absolutely.
Now, will that impact who becomes President? It's very doubtful because that state is highly likely to go to Biden. However, could that many votes impact local races? You bet. Could those ballots cancel out the legitimate votes of people voting for another candidate? You bet…and again, could we even be sure if it happened or didn't? Not really. Could this be happening on a larger scale in other places where national races could be impacted? Absolutely.