Their play can drop and they can be injured too, players don't generally get less injury-prone as they age. I don't think the team has been improved at all over the course of this off-season.
So you expect them to miss as many games? Okay. That's all we need to know on your opinion. You expect them to roughly play half a season combined.
The team, especially up front, didn't have to be touched to be improved. It's really not that hard to comprehend. When Datsyuk and Zetterberg were both in the lineup this past season, Nyquist, Helm, Sheahan, and the likes weren't.
The team was never fully together due to injuries and roster changes.
When we had 13 and 40 healthy, we had no depth because the lineup was full of Samuelsson, Bertuzzi, Cleary, Emmerton, Eaves, etc.
And when 13 and/or 40 were out, Nyquist, Tatar, Sheahan, Jurco, and Glendening all emerged. And to top it off Helm got healthy.
But throughout the season we never got to see the best of both worlds.
Unless there's a bunch of injuries in training camp, we actually get to start the season with the best of both worlds. Jurco being the only exclusion.