Looking where Van Aert lost time on Pogi/Vingo:
Stage 5 to Arenberg: +13 on P, s.t. V [no doubt he could have won time on both if he had gone all out for himself]
Stage 6 to Longwy: +7:28 on both [VA attempting a ridiculous 150km solo, not a bad day for him]
Stage 7 SPBF: +11:02 on both [possibly a bad day for him]
Stage 9 Aigle: +11:40 or so [all day breakaway]
Stage 10 Morzine: +2:30 or so [bad day?]
Stage 11 Granon: +17:27 on V, couple minutes less on P [another huge breakaway effort, and doing lots of teamwork]
Stage 12 Alpe: +15 [massive work for the team, pulling the peloton all day]
Stage 14 Mende: +6:30 [led peloton into final climb, maybe not a great day?]
Stage 17 Peyragudes: +21:20 [in the break, then piloting Vingo]
Stage 18 Hautacam: +2 V, +2 P [obviously a fantastic day, didn't even go all out in the end]
It's impossible to judge where he would stand in the GC if he didn't have to do team duties and wasn't such a lunativ, but I'm not sure, he had an actually bad day at all in this race so far - except maybe stage 7 and 14. Did I miss something?