The 22-year-old Australia international, who has played much of his football in midfield, lined up in central defence on Tuesday night as Boro fought back from 1-0 down to win 2-1 at the Riverside Stadium.
Mowbray told the club's official website, www.mfc.co.uk: "Rhys is a Rolls Royce really. He covers the ground so effortlessly.
"When he tackles, he reminds me of Gary Pallister. He's got these like snake legs, an extension gadget leg that comes out.
"You don't think he's going to get there, but he manages to make great challenges and great tackles.
"I'm pleased for Rhys. Whether that's his position, we will wait and see. Stephen McManus will probably join the squad on Saturday and Andrew Davies is knocking on my door every day to tell me he's just about ready, so the competition will be there in a week or two."
Source: PA
Source: PA