They had a pretty rough start but managed to grow into the game and became consistent in their performance. I could remember how they nearly lost to Chelsea in their first game but ended d match as a draw, played a few more games with Bournemouth and Newcastle which they managed to win but wasn’t good performance though. They had this average performance going on for a while and still managed to win matches, no one saw them coming because they don’t play well and gradually they got to top 4 and were just some points behind Arsenal until Arsenal dropped points and they took the top spot.
I don't sure with Chelsea performance in this season will get Champion League spot standings because their performance inconsistency and unpredictable result against mediocre teams with losses many points. Current points left with Arsenal on the fourth standings is 12 points and its not easy for Chelsea if can return to consistent performance. Have two consecutives winning matches in Premier League can't guarantee with promising performance for Chelsea on upcoming match Fulham exactly busy schedule match have to play on FA Cup 3rd round against Preston and few days later will face Middlesbrough on EFL Cup semifinal first leg.
Pochettino must make rotation on upcoming two matches because if push main players have to play on first minutes will make them loss opportunity in domestic league.