Pierzynski, a teammate from 2009-12 with Rios on the Chicago White Sox, said the Rangers are getting one of the most talented players in the American League. Rios has 12 home runs, 26 stolen bases and eight outfield assists this season for Chicago.
"He legitimately is one of those five-tool guys," Pierzynski said. "I've seen Alex at his best and at his worst. When he's right, there's not a lot of people that are better than him."
Rangers general manager Jon Daniels went to Pierzynski weeks ago to ask him about Rios when the Rangers were exploring a deal for the 32-year-old outfielder before the trade deadline. Pierzynski signed off on Rios as a player and as a teammate.
"I told him I would take him in a second," Pierzynski said. "His talent and his track record and as long is Alex is Alex and plays the way he can, then he can help us.
"He's a fun guy to have around. He's very talented. He can help. He can do numerous things either offensively or defensively."
Another former Rios' teammate when they were in Toronto, Jason Frasor, was asked how Rios would fit with the Rangers.
"It's hard not to fit in here," Frasor said. "You're free to be yourself. And there are guys here who police the locker room."
Pierzynski predicted Rios and shortstop Elvis Andrus will become fast friends.
"Him and Elvis dress similar so that will be good," Pierzynski said. "They can talk about fashion. They both wear really tight clothing.
"Alex will fit in perfectly. He's quiet, but once you get to know, he's fun. He's competitive."
There's also the part of Rios going from the last-place White Sox to the first-place Rangers. That can only be a breath of fresh air.
"Hopefully coming here will invigorate and give him a shot of energy and help us win the pennant," Pierzynski said.