Definition of "seamhead"

But the sport is an old flame for romantic types, as proved by numbers even sabermetric lords can wrap their seamheads around.

2007 October 15, Selena Roberts, “Football Is Booming at Baseball’s Expense”, in New York Times‎

He was a baseball lifer, a seamhead through and through, who just absolutely liked nothing better than sitting down and talking baseball.

2018, Adrian Dater, 100 Things Rockies Fans Should Know & Do Before They Die