Blocked shots weren't an official statistic during Ludwig's NHL career, so it's impossible to measure how many scoring chances he got in the way of during his 17 seasons as one of the League's best defensive defensemen during the 1980s and 1990s. At 6-foot-3, 220 pounds, he was a classic stay-at-home defenseman who knew how to play physically without taking needless penalties, was excellent at reading plays and adept at anticipating what opposing attackers wanted to do.
The Montreal Canadiens selected Ludwig in the third round (No. 61) of the 1980 NHL Draft, and he joined them for the 1982-83 season after three years at the University of North Dakota, where he helped UND win two national championships. He finished with 25 points, all assists, as a rookie and again had 25 points (seven goals, 18 assists) in 1983-84 -- but never came close to those numbers again.