It's a mistake to read a lot into the question-type breakdowns in a single ESR. They're based on a very small sample of questions, so the margin of error is enormous. You should only consider them meaningful if they confirm impressions you had during your prep leading up to the test.
I'd be especially reluctant to read a lot into your ESR CR score since your Quant is so strong. It would be fairly rare that a test taker that good at Quant would be weakest at CR among the three Verbal question types (not impossible, but rare). If, during your prep, you had the impression you were weakest at CR, then your ESR is additional data pointing to that conclusion. But if during your prep you had the impression you were strong at CR, do not let one ESR change that impression.
It appears on this test two things were true:
- On Quant, it seems you were unlucky. In the first 3/4 of the test, you clearly performed at a Q50 level. On the last quarter of the test, your hit rate was similar to what a random guesser would get. You had more than 9 minutes though for that part of the test, so you probably weren't guessing randomly at every question. When you did, your guesses were unlucky. If it was true on this test that you rushed through the last quarter of the test, spending about 1m20s per question, you should change that. Notice how low your hit rate was doing that (and that's what almost every test taker would notice). If instead you had invested a full two minutes solving four questions properly, four questions that at first glance you thought you could answer, then you often would get four right answers, and quite often guessing at the other three questions you'd get one of those right too. So you could, with a small pacing adjustment, get five right answers at the end instead of two, and that would secure a Q50 for you.
- conversely, and this is probably not something you'd like to hear, it appears you got a bit lucky in Verbal. You were short on time at the end, but your hit rate was strong in the last quarter of the test. So your guesses probably worked out better than average there. That said, your ESR confirms what you say in your debrief: "blacked out in first 5-6 questions in verbal". You got off to a bit of a bad start because of that. Had that not happened, your score surely would have been higher. Many test takers describe their test day experience in a similar way ('blacking out' for part of the test), and if you can figure out how to ensure that doesn't happen, your performance on test day will be more in line with your performance on diagnostic tests. It's an issue unrelated to your ability level, and is instead related to test day anxiety. It's not something prep books or GMAT experts are generally qualified to help with. Instead you'd want to learn what you can from psychologists specializing in test anxiety and related issues. Otherwise your Verbal ESR looks quite normal -- you got the easier questions right and the harder ones wrong, from the difficulty graph. If you could learn to answer more of the medium-hard questions, probably across all three question types, your Verbal ability will improve, and your score will increase as long as you can perform normally on test day. So you should probably focus on practicing medium and medium-hard official questions (revisiting ones you haven't seen in a while, if you've done all available problems before), and try to work out why you got them wrong, and what you need to do to answer similar questions correctly in the future.
You're very close to the 700+ level, so if you can find a way to address the issues you've had, you should be able to get an even better score quite quickly (and a 670 is not bad at all). Good luck!