At his peak, Green was the better offensive player. He scored 31 goals with the Capitals in 2008-09, making him the only defenseman to score more than 30 goals in a season since Kevin Hatcher had 34 for Washington in 1992-93.
In 2008-09 and 2009-10, Green was named a First Team All-Star and finished runner-up in each season in voting for the Norris Trophy. During those two seasons, he scored 149 points (50 goals, 99 assists) in 143 games, 34 more points than any other defenseman.
Shattenkirk made his debut the following season in 2010-11 and has the edge in scoring since.
Green has 240 points (69 goals, 171 assists) in 459 games, which ranks No. 24 among defensemen and is 0.52 points per game. Shattenkirk, now with the New York Rangers after leaving Washington as a free agent, has 321 points (73 goals, 248 assists) in 536 games, which ranks No. 11 and is 0.60.
Shattenkirk's scoring advantage during that time comes on the power play. At even strength, Green and Shattenkirk are almost even (0.299 to 0.296). With the man-advantage, Shattenkirk's scoring edge is 0.295 to 0.224.
In terms of usage, Shattenkirk and Green have been deployed similarly. In 2016-17, at the time of the trade, Shattenkirk ranked fourth on the Blues with an average of 16:22 per game at even strength, 0:22 killing penalties and 3:07 on the power play. He was starting 57.42 percent of his even-strength shifts in the offensive zone, highest among Blues defensemen.
Green has been assigned the same role for much of his career. In 2015-16, his first season in Detroit after signing as a free agent, he ranked fourth with 16:51 per game at even strength, 0:08 killing penalties and 2:46 on the power play. He had a zone-start percentage of 69.61, the highest among NHL defensemen to play at least 20 games.
Green was transitioned into the No. 1 role in Detroit as the roster started to change. During the past two seasons, he has averaged 20:01 per game at 5-on-5, which ranks sixth among NHL defensemen.