The expectations for Oakland Raiders linebacker Khalil Mack, set to embark on his second NFL season, continue to grow.

Mack, the fifth-overall pick by Raiders GM Reggie McKenzie in the 2014 NFL Draft, entered the league with quite a bit of hype and promptly delivered, amassing 76 tackles, 16 for loss, four sacks and a forced fumble in what turned out to be an extremely promising rookie year.

Mack added mass this offseason in the hopes of upping those totals further in Year Two and according to teammate Curtis Lofton, it's already making a significant difference.

"Monster," Lofton said recently, per Scott Bair of "He's young, but he's got so much more. I'm really impressed with him. He comes every day to work. He studies and goes out there and executes it on the football field. Some guys, if they have a good year that first year as rookies, they are Mr. Joe Cool. That's not him. He comes to work every single day."

Lofton isn't the only one who has noticed the 10 to 15 pounds of muscle Mack added.

"We asked our guys to come in and eat right and train hard, and then I really trust [head strength and conditioning coach] Joe Gomes and his staff to help us establish healthy, productive weights for our guys," Raiders coach Jack Del Rio said after Tuesday's OTA session, via Bair. "As you know, Khalil doesn't carry a lot of body fat. He's added some lean mass and he's put on good weight. We feel good about where he is."

If Mack can improve upon his rookie numbers, especially where the pass rush is concerned, it will be a benefit not only to his own cause, but that of the entire Raiders team.

The more havoc Mack creates in the opponents backfield, the less time a suspect defensive secondary has to spend in coverage, meaning the entire defense will be able to get off the field on third-down much more often than they did in 2014.

And the less time the defense spends on the field, the more opportunities young franchise quarterback Derek Carr and the offense will have to put up points.