The biggest reason of all was because of the gap in quality of Real Madrid versus Chelsea in their respective leagues, in mourinho's time at RM La Liga was a two horse race between them and barca, with both teams having vastly superior players than any other team in Spain, hence their quality would shine through and they would often score lots. In Chelsea the playing field was much more even across the league, yes he did Park the bus sometimes, but that was due to the dip in form or the nature of the team he was against (Arsenal comes to mind) rather than it being mourinho's style, whereas there were games where they absolutely blew up lower table teams. Think of it like Van Gaal against the big clubs we often were defensive at times but still won more often than not, plus mourinho will give us those high scoring games against weaker teams.