A significant caloric deficit diet isn't sustainable long term, and I assume that is what Vlad was on this off-season because there really is no other way to shed 20+ lbs in such a short period of time. Even staying at a maintenance calorie intake is probably hard for a guy who is used to consuming X calories during a major league season and thus some weight gain is to be expected as you said. More lasting and meaningful body shifts take longer than one season to accomplish, it requires a lifestyle change and time.