All three judges scored the fight 120-107. Andrade, who previously held the WBO and WBA super welterweight titles, improved to 28-0 with 17 knockouts. He made the second defense of the title he won last October.
"I'm the best out there," Andrade said. "I had to step up to the plate." Andrade dropped Sulecki (28-2) with a left hand in the first minute of the opening round. He largely stayed at a distance from there, landing punches from the outside. In the fifth round, Andrade switched from his normal left-handed stance to a right-handed stance and toyed with Sulecki, winding up his right hand before throwing a left jab.
Andrade tried to put on a show for the 7,136 fans in attendance. Between the 11th and 12th rounds, he left his stool and sang along as "Sweet Caroline" played, just as it does at Boston's Fenway Park in the eighth inning.
After the fight he called out Canelo Alvarez, the owner of the other three major middleweight championships, as well as former champion Gennady Golovkin. "Canelo, let's get it on," Andrade said. "I've been beating these guys. Where's Canelo? Where's Triple G?"
Sulecki was the WBO's top-ranked contender. In the co-main event, former WBO heavyweight champion Joseph Parker of New Zealand stopped Alex Leapai of Australia in the 10th round of a scheduled 12-round non-title bout.
Referee Ricky Gonzalez stopped the fight at 2:18 after Parker drilled Leapai with a right hand that forced Leapai to stumble backward briefly. "I've been out of the ring for half a year," Parker said. "It ended up going more rounds than I expected. I just had to be patient."
Parker (26-2, 20 knockouts) pressured Leapai in the early rounds, attacking him with several hard right uppercuts. Midway through the fight, Parker resorted to boxing, staying on the outside and landing quick combinations.
In 2016, Parker won the vacant WBO title with a decision against Andy Ruiz, who stunned Anthony Joshua last month to win the WBO, IBF and WBA titles. Parker lost to Joshua on March 31, 2018. "I want to avenge the losses to Joshua and Dillian Whyte," Parker said. "I could fight Ruiz again. He thought he won the last time."
Leapai, a former title challenger, dropped to 31-7-4, with 25 knockouts.