The 28-year old is a three time pro-bowler (albeit not since 2010) and has surpassed 1,000 rushing yards in each of his six seasons in the NFL.
At this stage, it's worth emphasizing that there have been no direct links between the Jets and Johnson, although this NFL.com article identifies the Jets as a "potential landing spot" and Rich Cimini has pegged him as a "name to watch" if he gets cut.
What's impressive about Johnson is that he's a legitimate three-down back in an era where that's a dying breed. Not only has Johnson not missed a game in five years, he's also been in the top six for total snaps by a running back in each of the last four seasons. He therefore has a lot of experience on passing downs, both as a blocker (has stayed in to block 99 times on average in each of the past three seasons) and as a pass catcher (272 career receptions).
The downside with Johnson is that this workload might be starting to erode his trademark explosiveness. His yards per carry average dropped from 4.5 to 4.0 in 2013 and his longest run was just 30 yards, after he had rushed for three touchdowns of 80 yards or longer in 2012. He might therefore benefit from a reduced workload that would keep him fresh deeper into the season, as was the case when LaDainian Tomlinson joined the Jets and split carries with Shonn Greene. Tomlinson increased his yards per carry average from 3.3 in 2009 to 4.2 in 2010. Johnson is two years younger than Tomlinson was when he joined the Jets.
Interestingly, however, the NFL.com article above suggests Johnson is overrated as a receiver because he has poor hands and versatility, and that his receiving numbers are misleading because he catches a lot of dump-off passes. He may therefore not be as ideally suited to the Tomlinson career path as we might initially have thought.