Acquired in a Minor League trade with the Astros on May 26, Ruggiano was promoted to the big leagues a day later, and he is starting to receive more playing time.
On Friday night, Ruggiano doubled and had two walks in the Marlins' 12-5 loss to the Blue Jays. Even though he lifted a foul popout in his final at-bat, he worked the count full.
"He gives you great at-bats," Guillen said. "He fights for his at-bats every time we give him an opportunity.
"As long as you do that, you will play for me, no doubt. I don't care if you're 0-for-4. As long as you fight for your at-bats and your situation, you have a great chance of playing for me."
The right-handed-hitting outfielder has mostly played against left-handed starters, and that is a reason he was in the lineup again on Saturday. Toronto went with southpaw Brett Cecil.
Ruggiano, who came up in the Rays' system, credits Tampa Bay executive vice president of baseball operations Andrew Friedman for changing his approach.
"I used to give away a lot of at-bats, and I think in the Rays' system, strikeouts are kind of frowned upon," Ruggiano said. "They're frowned upon anywhere, but it was something they wanted me to focus on, reducing them. For the longest time I couldn't figure out how, and it was frustrating.
"I think I came up with a pretty good idea of what works for me and how to stay on the ball longer. That's kind of what I was doing, coming off of it, and sometimes I revert back to it -- hitters go through that. But basically it's me trying to stay on the ball and use the whole field."