Summer was a massive missed opportunity for them, with CL on offer they could've added more quality to their XI and squad but failed to capitalize that opportunity and as a result you get performance like Saturday with 2 first teamers out. I look at their starting XI and it's basically last years team with exception of Wanyama, who has done well this season but his limitations were exposed badly against Liverpool.
Also, they are extremely over-reliant on their fullbacks and Eriksen for any creativity. Eriksen especially who is at heart of everything they create through the middle. Once Liverpool crowded him out on Saturday they couldn't get going. Alli is also being utilized further forward this season, Wanyama has taken position of Dier and is nowhere near as good on the ball which means burden has increased on Dembele and Eriksen to provide any quality through the middle. Role of full backs has also increased this season, Walker and Rose to their credit have delivered so far but an injury to either of them and it has a massive impact on their game. While Tripper is a good substitute for Walker, Davies is far from an appropriate solution in absence of Rose.
It's premature to write off their chances of silverware this season and while Top 4 race remains wide open, Spurs have to spend big this summer and add more quality because if the ambition is to compete on all fronts. You need to have dependable options off the bench.