Obviously, in a perfect world, you'd simulate the whole match like FM 2006. However, this is really really out of league for a web game like yours, so you'll have to come up with something simpler. One problem with the "take the result and build the game scenes around it"-approach is that it becomes rather meaningless, at least as soon as the player realizes this. In the end, it'd still be down to a game of numbers, as all you could do with your decisions would be to optimize your number. It is hard to get around, but it has totally destroyed more than one manager game for me.

What might be worth a try would be using text for description of the matches. You could have chances, and depending of the skill of the player with the ball and other players interacting with him, his skills would actually mean something. For example, say we had randomly decided that Player A who has the ball is tackled by player Y, then you could now compare the attributes of these players and determine the odds of each player winning and go from there. It might still become quite complex, depending on how much variation you want in the game, but I think it might be more interesting. I think there is actually a (german) web football manager which does it like this, but I can't remember the name right now.

I think this is a pretty good compromise between the two, because it still offers the possibility of actually creating meaningful situations without having to simulate all of it. It is still pretty complicated, though, so depending on how complex you want the game to be, it might be too much.