It may be hard to believe after two blown fourth-quarter leads in the first three games of the season, but the Giants are getting some of the best quarterback play of Eli Manning’s career.

In three games, Manning has completed a career-best 65% of his pass attempts and hasn’t thrown an interception. His quarterback rating of 97.9 is almost five points higher than his career high for a full season, which came in 2009 (93.1).

Much...