It's not unusual for Chip Wilson to have some choice words about the team now running Lululemon, the Canadian yoga wear company he founded.
While Wilson remained critical about the brand's performance since he exited the CEO role in 2013, he told CNBC on Friday that Lululemon has a better business model than another major player in the athletic wear space: Under Armour.
The outspoken Wilson, who remains one of Lululemon's largest individual shareholders, recently placed an ad at a bus stop outside the company's Vancouver headquarters. The ad instructed Lululemon to buy Under Armour.
"Lululemon's way more profitable," Wilson told CNBC's "Squawk Alley" on Friday.
The opportunity for Lululemon is particularly ripe because Under Armour's market share has gotten whacked over the past few months, Wilson said. The label recently reported a dramatic slowdown in sales, which Wilson attributed partly to Sports Authority's bankruptcy. The shuttering of that chain's 450 stores has contributed to bloated inventory levels in the athletic space, forcing markdowns.
"It's super weak right now," Wilson said, adding he "wouldn't want to be working at Under Armour right now."
Spokeswomen for Under Armour and Lululemon did not immediately respond to CNBC's requests for comment.
Wilson said he decided to take out the ad because he "couldn't effect Lululemon within the board." He stepped down from the board in 2015 but has remained vocal about its decisions. Last year, he wrote a letter to shareholders saying the company had "lost its way" and fallen behind competitors. At the time, he listed Under Armour as one of those competitors.
Wilson's tenure was rife with conflict. Following a product recall that caused its Luon yoga pants to pill and become sheer, Wilson made comments that they weren't meant for all women's bodies.
Lululemon shares have gained 7 percent over the past year on sales and margin momentum. In January, the company raised the low end of its fourth-quarter sales and earnings outlook, citing a "strong holiday season." That followed a rosy third-quarter report when it beat on both the top and bottom line.
Still, Wilson isn't impressed with the company's results.
"The Lululemon stock is exactly where it was six years ago," he said, adding it's "quite foolish" to get excited about a few months of good returns.
Lululemon shares were last trading at $65.56 on Friday afternoon, compared with their 2011 high of $64.49.