Once the dust has settled after free agency period, a lot of players change teams. Some fans will be really happy about the players they acquired and promise that the Cup is just an afterthought while other fans will despair and kiss the playoffs good-bye. Regardless of what happens in free agency, after the players sign, all they are is, simply, names on a page. No matter how it looks good or bad the teams look on paper, it's how they play together that matters.
There are numerous teams in history that have put together All-Star teams and fallen on their faces. Look at the New York Rangers in the late 1990’s, before the cap was instated. So many famous names lined the scorecard, but no cups. They continued to dwell in the mundane confines of mediocrity. Also, look at the 2003-2004 Colorado Avalanche. Teemu Selanne, Paul Kariya joining such illustrious names as Joe Sakic, Peter Forsberg, Adam Foote and Rob Blake, yet no cup came to Denver that year, it went to the Lightning who, at the beginning of the year were picked by "The Hockey News" magazine to finish sixth.
Some teams don't look great on paper, but achieve a lot. My favorite example is Western Conference playoffs in 2006. The matchups were all a heavily favored team against an underdog team. Every series was supposed to be relatively easy. Detroit Red Wings were supposed dominate the Edmonton Oilers, the Dallas Stars the Avs, etc. However all four lower-seeded teams upset the higher seeds. Even after their first round upset, the Oilers continued to march through the playoffs. The ultimately lost to the Hurricanes but still went three rounds longer than they were supposed to.
So, no matter whether a team signs Jesus to play with them or a team does absolutely nothing, the signings in July and August do not guarantee a cup. The names on the page don't matter.
Will the team be cohesive? Will everyone buy into the coaches' scheme? Will the infamous injury bug strike? All these questions help answer the question of "who will win Lord Stanley's Cup?" That question will be answered in June, not July or August.