Friends always had a great gift for taking absurd setups, and making you buy into them, even when the plotlines became really goofy. "Rugby" is an example where that didn't happen successfully. I love the Janice/Chandler episodes; no matter how annoying Janice was, she was still funny, and her effect on Chandler was usually priceless. However, in most cases, Chandler usually had a stake somehow in that relationship, so it made weird sense that he could never seem to let go, and would react to her in bizarre ways. In this episode, Chandler had no reason to feel timid around Janice, no reason to be "Chandler-esque". Janice was simply being pushy, and Chandler abandons his cojones entirely, which was just pathetic. The whole escape to Yemen thing was not silly fun, it was just stupid (although "Yemen Express" is a funny airline name).
Add to that the over the top obsession Monica has to find out what's on the other side of a electrical switch, and Ross's willingness to kill himself playing rugby to indulge his jealousy over one of Emily's friends, and you have a clear-cut example of Friends at its worst. This episode tried way too hard to be nutty, and ended up looking foolish.