Right now it's unclear if Johnson will miss the entire season. Johnson went down in practice on Sunday. We just posted a news item today from the San Diego Union-Tribune talking about what the Chargers may have to do if Johnson is out for an extended time, which certainly seems to be the case. This particular beat writer pointed to Tyrell Williams as a possible replacement on the outside with free agent Travis Benjamin opposite of him. That would move Keenan Allen to the slot - and the Chargers do play a lot of three-WR sets. Javontee Herndon is another possible replacement for the slot which would allow Allen to stay on the outside. Dontrelle Inman is also on the roster.
Our own sports physical therapist Russell Manalastas weighed in on Johnson's injury: With any torn meniscus the important thing to consider is the size and location of the tear. The meniscus is a cartilage that lacks adequate blood flow so location of the tear is really important. One option would be to do a menisectomy where they just take the portion that is torn out to prevent the knee from catching, lacking, or buckling on him. The other option would be a meniscal repair, where they stitch the torn area back down to preserve the meniscus and preserve the knee from degenerative changes later on. With this being the NFL and how things are always expedited, my guess would be that if they can, they'd clean up the area that was torn, shave it down so there are clean edges, and then start the rehab process. Menisectomy timetables are significantly shorter in terms of recovery (4-6 weeks, depending on pain tolerance, strength and other factors), whereas meniscal repairs are a much longer recovery (4 months or longer, and that's being optimistic). Once we find out what type of surgery Johnson has, then we can figure out what the expectation should be.