I tried to help him. He is unbelievably hard to teach. He may have been having session exit style that shaped results to favor huge losses. The rest are in the thread. But what I think is happening is what I call the perils of deep pen. He probably knew which dealers to play for deep pen. At deep pen many things happen that can mess you up. First as you play through a shoe the granularity of deck estimation depends on the ratio of the RC to the number of decks remaining. If your RC is +4 with 4.5 decks left you could be using estimates by 2 deck accuracy and it won't make a difference (4.5 decks is 6 decks remaining) the TC calculation will be the same as if you used 5 decks. But if the RC is +15 the TC calculation would be +3 for full deck accuracy and TC +2 for 2 deck accuracy and full deck estimations. If the RC is +50 you want 1/2 deck accuracy. Half deck accuracy gets a TC of +11, while full deck accuracy a TC of +10, and 2 deck accuracy would get a TC of +8. You need to consider how your sim does it. My sims use 1/2 decks accuracy with the discards floored so you never underestimate the cards remaining. At deep pen underestimating is a much larger error than over estimating cards remaining. Anyway once you get to deep pen, below 1.5 or 1 deck, you need to be estimating at 1/4 deck accuracy or your TC is way off. You need to be accurate or your TC is way off. Many people have trouble with 1/4 deck accuracy with over 5 decks in the tray. The places that give great pen usually do everything they can to make deck estimation hard. They might use cards that are very thin, use different discard tray sizes at different tables or instruct the dealer not to bang the shoe to have gravity make looking at the shoe fairly consistent for info. Some have tilted bottoms to the discard tray so one edge is a quarter deck higher than the other. Some have the discard tray set into a hole on the table so the bottom of the discards sit closer to the felt while others have them higher off the felt than is standard. So if all this magicians illusory is successful at getting you to be at least 1/4 deck off at the end of the shoe that last bit of pen hurts you except when the TC is so high that you are max betting and over all your indices even with a 50% or 100% in deck estimation when calculating the TC for betting or playing decisions.

Two things determine how accurate you must be. The level of pen you are playing at and the magnitude of the RC. The truth is what matters is the relationship between the two. He was probably only playing the deep pen with an advantage (wonged out if no advantage) and was making too large of deck estimation errors or not estimating the same way his sim estimates. It could easily just be variance. I recently went on a trip with endemic EV of around $50/hr. Every day I was way over EV and 4 of 5 I was 6 sigma over EV. Actually I have some new information that confirmed my suspicion that I can't use my regular bet size because the side bet was an unrelated bet which I was playing at an advantage. The two bets had no correlation to each other so variance was amplified. That meant either I needed to bet less or my variance was much higher than I thought it was. The results of being up 6 sigma 4 days in a row says my variance was significantly larger than the sims of each play individually said it was. If so I was overheating or my RoR was much higher than I thought.