By Josh Rosenblat,Kevin Sweeney Plus, previewing Mahomes vs. Herbert. Good morning, it’s Josh Rosenblat and Kevin Sweeney, teaming up for today’s edition. Some big news came across the wire this morning, so let’s get into it. In today’s SI:AM: 🎾 Federer to retire 🏠 Tyrann Mathieu’s complicated homecoming 🏀 More fallout from the Robert Sarver punishment If you’re reading this on SI.com, you can sign up to get this free newsletter in your inbox each weekday at SI.com/newsletters. Roger Federer calls it a careerIt was not even two weeks ago that the tennis world sent Serena Williams into her life…