Something just isn't clicking for them this season. Bar the occasional brilliant performance (beating Stoke away 4-0 and beating City 2-0 at home), Pochettino seems to be finding it difficult to find his best XI.
Eriksen, Alli, Dier have all regressed compared to last season, whilst only Kane, Dembele and Lloris have performed to the same standards they did last season.
Sissoko has been a disaster of a signing, N'Koudou has been hardly been given a chance, Wanyama has been good in patches whilst Jansen it would seem just isn't good enough.
However, despite crashing out of the CL, they are still unbeaten in the PL which sets them in good stead for the rest of the season. Having already played Everton and Arsenal away and Liverpool and City at home.
Between now and January 3rd, they have five very winnable PL games. If they win those they should be on track for CL qualification once again.