Chelsea are knockout team, 2 underdog titles, gotta respect that. Plus they always had character team and good spirit. Something City, PSG and perhaps Barca are lacking for years already.
Add to the basket steady and safe rise in form. RM's last title is perfect example, Argentina in WC as well. Each match progressing they had more and more power which resulted in spectacular finishes.
Might sound beserk right at this moment, but I think if we manage to play few in form games, with roles of Lukaku, Gosens and Brozo back, we could eliminate Porto and become a serious player in quarters. From there at least 30% of chance to advance further. After all we kicked Barca out, look at them now.