While the idea of 'going with youth' is a nice concept, the reality of the situation is that young players go through various highs and lows in the first few years of their development. Unless you have a superstar prospect on your hands, it's likely that there will be an adjustment period. The key when going through such a slump is that you work your way out of it and don't let it determine your career as a player.
Luke Schenn is a good example of a player who went through the dreaded 'sophomre slump' in his second season with the Maple Leafs, but instead of letting it consume his season he was able to work his way out of it and ended on a stronger note. Nikolai Kulemin is another player who started slow, but found his groove as the season went on.
On the opposite end of things, forwards John Mitchell and Mikhail Grabovski had serious lows on the season. Both players weren't able to elevate their games to the next level, both suffered injuries, and both tried to do too much with the puck.
Now next season the Maple Leafs will have as many as six sophomore players on their roster and for the Maple Leafs to be a playoff team they'll need to have those players avoid prolonged slumps.
It's unrealistic to assume that all six of the returning sophomores Carl Gunnarsson, Jonas Gustavsson, Tyler Bozak, Viktor Stalberg, Luca Caputi and Christian Hanson will be impervious to slumps, but it'll be very important for the Maple Leafs that Gustavsson, Bozak and Stalberg can continue to elevate their games.
Carl Gunnarsson, should he slump, is at least solidified by a number of capable defenders (at least on paper). Luca Caputi and Christian Hanson won't be relied on to put up big numbers, so they too can at least be shielded from major scrutiny. Caputi being 21, may not even make the club out of camp next season.
Tyler Bozak will be looked on to at least fill a second-line center spot, which means producing at around a 50pt clip, while also being reliable at both ends of the ice. Viktor Stalberg had an up and down season, but really turned it on in the last 20 games and was starting to become a more dominant player on the puck. He too will need to be a secondary scorer going into next season. With Jonas Gustavsson, its' no secret - the Maple Leafs need him to be at least a 1b goalie. Someone they can rely on to tandem with Giguere and push him to be a better goalie.
With a lack of high-end free agent forwards on the market the Maple Leafs will rely on those three players to be main contributors next season. While the roster isn't set for next season, and a lot could change between now and then, the importance of quality depth is key for any team to be successful. If Bozak, Stalberg and Gustavsson fail to raise their games, we may be pointing to them next season as reasons why the Maple Leafs missed the playoffs for a six straight year.