The move was a rare early-summer, big-money signing from manager Arsene Wenger, which signals that the Frenchman recognized the need to improve and solidify his attacking options.
Arsenal may have just ended its lengthy title drought by capturing the FA Cup, but supporters are still hungry for an EPL title and to see their club contend for the Champions League.
Signing Sanchez is a big step toward both of those goals.
Not only does the Chilean international add another scoring presence (he scored more goals per 90 minutes last year than any of Arsenal's main attacking options) to a side loaded with creative playmakers, but he also brings versatility, something Wenger loves in his players.
Sanchez can play on both wings, as well as a centre-forward, giving the Gunners more flexibility in how they line up.
That also translates into added depth for a squad that was hit hard by injuries during the 2013-14 season.
The possibility of Sanchez and Theo Walcott playing the wings at the same time should also have Gunners fans salivating.
The pace that the two of them would bring would be breathtaking. Then there's the fact that they were both delivering key passes and creating chances at a high rate when they were on the pitch.
Walcott, himself, is confident that they will be a tough tandem to handle. "With me and him on the flanks, a lot of teams won’t be looking forward to playing Arsenal this year," Walcott said, via The Guardian.
Throw in a young gun like Alex Oxlade-Chamberlain and the likes of Lukas Podolski (should he remain at The Emirates), and you have an impressive collection of players on the flanks.
Sanchez's presence could also help take Mesut Ozil's game to another level. The German playmaker showed flashes of brilliance last year but was plagued by inconsistency and looked fatigued at times.
With another proven scorer added to the equation, Ozil should be able to find a more consistent game. Furthermore, Sanchez's pace and dribbling ability could open even more space for the reigning World Cup champion to exploit.
Finally, Sanchez has no problem contesting balls or playing right at defenders.
Take the 2014 FIFA World Cup as an example.
No one came close to drawing as many fouls or winning as many take-ons as the Chilean.
Not only is the 25-year-old star a fantastic fit for Arsenal, but according to him, the Gunners and their manager are a great fit for him as well. He told Arsenal.com that "Arsene Wenger's style of play is the sort of style the Chilean national team has. Therefore I am used to it. Arsenal plays very well, which fits my style. That's why I moved here."
Arsenal still may need to bolster a few areas of its squad, but adding Sanchez—and keeping him away from Anfield to boot—was a terrific way to kick off their summer dealings.
Jon Reid is a contributor to Bleacher Report. Follow him on twitter @JonReidCSM.