190-195 is good for the flat. 200-205 is good for the point. Sounds like your temp and resting time was fine. Was there a 1/4 inch fat cap on the top? Sometimes I find that when you buy a flat alone, the fat cap has been over-trimmed by the butcher or grocery store. Could try brining or injecting. Sometimes though, your just get a lean brisket, an animal that was just less lazy! Look for USDA "Choice" or "Prime" when it comes to flats. These days, the most common USDA beef in your average supermarket seems to be "Select" or lower. Sad but true. Not good for brisket flats, steaks, etc. Maybe acceptable for other cuts.