After two pitch inspections the game did get the go-ahead, but the rain was incessant as ever at kick-off time.
Stockport created the first chance after three minutes when Paul Turnbull released Liam Dickinson, but he fired into the side-netting. Adam Nowland then curled a great low free-kick inches past the post.
Both sets of players were finding it difficult to get a grip in horrendous conditions, then on 23 minutes Gareth Owen's backpass got stuck in the mud, but Stockport keeper Conrad Logan rushed out bravely to thwart John Sutton.
At the other end Nowland played in Proudlock, only for his shot to be well saved by Frank Fielding.
Defender Lewis Christon curled a shot over for Wycombe, then skipper Matt Bloomfield went on a mazy run before seeing his shot gathered by Logan.
It was Stockport who went in front on 35 minutes though. Michael Rose swung in a great cross and Proudlock slid in to fire home from eight yards.
Less than three minutes later it was 2-0 to Stockport when Dickinson spun on the edge of the Wycombe box before lashing in a super low shot in off the far post.
Dickinson went close again less than 30 seconds after the restart when he barged through before slamming a shot inches over the crossbar.
Wycombe hit back with Gary Holt seeing a shot saved at the second attempt by Logan, but it was Stockport who raced clear just before the hour mark when Dickinson flicked on for Proudlock and he produced a thumping finish to beat Fielding.
Minutes later it was 4-0 when Christon steered Dickinson's cross past his own keeper.
Proudlock's cool 45-yarder made it 5-0 as Fielding was caught off his line, then Russell Martin's own goal on 78 minutes completed a shocking day for the visitors.