Someone coming in with an additional ’10 pounds of muscle’ at camp is always a cause for celebration for fans of that team, but I’m skeptical usually. These guys are trained athletes, operating at or very near to peak efficiency, Dustin Penner or Kyle Wellwood excepted. To expect that they in three months packed on that much muscle is unrealistic, as we've discussed before in the case of Josh Gorges, who some fans would exhort to "put on fifteen pounds of muscle so he doesn't get ragdolled."
When a player reports ten pounds heavier to training camp, it’s often not 10 pounds of muscle, but more like 5 pounds of extra water weight from the creatine, 3 pounds of fat (not from laziness, just from being able to recover after hard training, rather than getting on a plane to Minnesota) and maybe 2 pounds of muscle in a best-case scenario, one of which would have been re-gained from the end of the season if the athlete had just sat on the couch, purely by recovering from the grind of the previous season.
Players weights fluctuate in other sports too, sometimes intentionally. We see this in the NFL, and it’s amusing, how a linebacker or a running back comes into camp significantly bigger, and he explains how he hit the gym hard and worked on getting stronger and more powerful. The next summer, he’s described as coming in ‘shredded, ripped’, and the player explains that he wanted to get lighter and more agile, faster for the season, and felt too bulky and heavy the previous season. And the cycle never ends. A lineman comes in bulked up and says he wants to dominate the line of scrimmage, the next season he comes in twenty pounds lighter and says it will help him in the running game and he hopes the coaches allow him to ‘pull’ more and take on linebackers and safeties in the second level.
Murderer-at-large Ray Lewis yo-yoed from heavy to lighter to heavy again during his career, and he always rationalized it as needing to stack the line of scrimmage one year, then the next saying the scheme will be different and he needs to cover tight ends in the passing game. He credited bicycling for his loss of weight at the end of his career, but then ripped a triceps in his final season, which is normally a season-ending injury. Ray miraculously returned for the playoffs, and there were whispers about how huge he looked, how he’d packed on pounds, which is kind of hard to do for your upper body if your triceps is out of commission and you can’t bench-press, but anyway, no reporters wanted to get fatally stabbed so no one pushed the issue too far, even when the deer-antler spray malarkey surfaced. Anyway, no harm no foul, Ray must be a good guy, he’s a woofer for ESPN right along with MeShawn John$on.
We're not discounting that a player can put on muscle and benefit, especially when they come in after a summer of hard training, but it needs to be kept in context. Normally, a player will come in heavier than at the end of the previous season, just from having recovered from the previous season’s grind. So a smaller Brian Gionta will be two or three pounds heavier at camp maybe, while a larger Hal Gill or Douglas Murray will be five or seven pounds heavier. Then, the stress of the season, the exertion and the travel will wear them down again by the next spring.
Young players will come in with more significant weight gains, from natural growth and filling out, going from teen to man. So a an eighteen-year old Brett Lernout will 'recover' five pounds, possibly add another five pounds naturally, easily, through natural growth and training, so he’ll roll into camp ‘ten pounds heavier’. Journalists routinely add ‘of pure muscle’, but that’s not necessarily so.
As players age, the weight gains should become less noticeable. Jarred Tinordi is probably in the last year or so of coming into camp significantly heavier than the previous season. At 22, he’ll be pretty close to filled out, and his weight should stabilize for the rest of his career, he might add a pound a year the rest of the way.
A special case might be Nathan Beaulieu. He’s 21, still filling out, and he reportedly has never really dedicated himself to his physical conditioning, but is doing so this summer. Since he’s starting from a relatively untrained base, he has a lot of low-hanging fruits to pick, lots of room to grow, so he might make relatively large gains in size and strength and power in the next couple of years, until he gets closer to his ceiling and his gains become incremental.