Pronunciation and meaning: "wind" and "wound"

The sound /w/ had a large impact on the following vowel in the Great Vowel Shift. Consider: the combination war should be pronounced like car, but usually is pronounced like bore—consider warp, ward, warm, quarter, quarry, dwarf. The combination wor should be pronounced like bore, but is usually pronounced like burr—consider work, word, worship, worry, worm, worse.

Why does /w/ have this effect? I have seen the explanation that you round your lips for /w/, and this means there is a tendency to round the following vowel as well. This explanation accounts for the different pronunciations of wound (as the OED says), but I don't believe it can account for wind, as the vowel is not rounded in either pronunciation of wind.

Why one of wind and wound was affected and the other wasn't is unclear, and is probably not the kind of question anybody can answer.