The visitors finished the game with nine-men, but still managed to win with Gustav Isaksen striking on 98 minutes for the 2-1 Europa League round 16 first-leg triumph.
“I am very happy for the lads, it was a difficult match because we lost our way a little and were running out of steam in the second half,” Baroni told Sky Italia.
“Plzen are aggressive, they press high, attack, run hard, while it is also difficult just to control the ball properly on that pitch. This all makes the victory even more valuable.
“The character of this team was on show again, the sheer hunger that they have. It is another step forward in our growth process.”
Nicolò Rovella and Samuel Gigot were sent off for Lazio, but Baroni's players still managed to find a way to win.
“I think this was our 19th goal of the season scored in the final 15 minutes plus stoppages, so that is a sign that this team always believes and never gives up,” added Baroni.
“I am pleased at Isaksen’s goals this season, but not surprised. He always needed more confidence and I gave him greater freedom, as I like a striker who takes risks. He is starting to be decisive now and I always felt he was ready to explode onto the scene.
“It is my philosophy that we must always try to attack and get bodies into the box, so I kept forwards on the field, even down to nine men.”