Ok so here's my story and use of this tactic....
I took over swansea after a couple seasons into the game and built them up, buying good young regens to develop and big names who had fallen out with clubs and available for a bargin.
The last couple of seasons we've managed to get into the top four but couldnt make that step up to challenge for the title. About a quarter into my latest season I started using your tactics, the 442 and the underdog. It was going well but wasnt stable. Then for the last third of the season I used your 4141 rock and we became a brilliant side. Consistent form led us to challenge for the title and win it on the last day of the season!! by beating arsenal into second place.
oh, and we also won the champions league! in a tight 1-0 against man utd.
While the rock tactic is great at keeping clean sheets, now and again it does have brilliant attacking, this result being a particular highlight