When they feel strongly about their case, plaintiff and defense medical malpractice attorneys tend to shoot for the moon to get “the guy” to be their expert. But jurors in malpractice cases understand that doctors are generally pretty qualified. Relative degrees of qualification are less nuanced by a jury. But what they do appreciate is experts who are paid an obscene amount of money have a motivation to lie. Jurors also prefer a medical expert who is a good teacher that explains complex problems in a way they can understand. This is more important than a Harvard fellowship.
A related overreach many medical malpractice lawyers make when trying to get “the guy” is getting a subspecialist to render a malpractice opinion on generalist. For example, don’t hold the general ortho to the world renowned foot and ankle guy. While there is clearly a floor that is the standard of care, jurors are going to be hesitant to hold every doctor to the standard of “the guy” in a subspecialty to a doctor who has a more general practice.