I'm not talking about the CL. I'm talking about their results under Inzaghi in Serie A league compared to Napoli. Their squad is rated at about 600m, Napoli's is at 350m roughly, and they could lose a league title to Napoli.
That's very very bad.
In CL they did pretty well. Domestically, not so much.
The squad transfer 'value' from Transfermarkt is based on much more than how good the players actually are. They are an estimate made by volunteers of what they think the players will sell for, it is based on hype, age, recent performances etc.
A good example is that Lukaku is valued at 22m and Thuram is valued at 75m, but Lukaku in Italy was considered the best striker in the league during his time at Inter and still is one of the best there. The performance difference between them isn't 50m but Lukaku is older and has very high wages which reflects in the value.
Inter have had a disappointing domestic season however it is clear their charge has suffered by competing on three fronts, they managed a good lead before the last month of games. There is no easy option there for a team that has many old starters and a lack of depth.