The Penguins are painfully aware of the unpredictable, often frustrating nature of head injuries and related problems. Team captain Sidney Crosby missed most of a 15-month span and had a comeback thwarted because of a concussion and neck injury he got in January 2011. While the club is not ready to categorize the injury to its other star center, Evgeni Malkin, there are indications that the Penguins are willing to err on the side of caution and be patient. Malkin did not participate in an optional practice Saturday at Southpointe, and he has been ruled out for the game tonight against Tampa Bay at Consol Energy Center. He left the 3-1 victory Friday night against Florida in the third period after slamming into the end boards, hitting his back and head and snapping his neck in a whiplash motion. Coach Dan Bylsma, the only one to address Malkin's situation directly Saturday, referred repeatedly to the NHL protocol. That is an indication of fear of a concussion because the league protocol is designed to detect such head injuries and keep players out of the lineup until they are fully recovered. "He is still getting evaluated as far as the hit and going into the boards hard," Bylsma said. "That's an ongoing process at this point. When we have more information, we'll give it to you." He said based on what Crosby went through, the team is in a waiting mode with Malkin.