I'm relatively pessimistic about Lynch for this season. Most RBs hit a wall sometime around the age of 30. Once a RB reaches his late 20s, each year is a roll of the dice as we wait to see if he still has what it takes, or if the extra year of aging / accumulation of injuries has reached the point where he isn't a good RB any more.
That leads in to two big concerns about Lynch. First, his last good season was in 2014, at age 28. Now it is 2017 and he is 31 years old. That means means that he needs to survive 3 rolls of the dice and not just one. Did his body hit the wall at age 29? At age 30? At age 31?
He had a great season at age 28, now let's see what he does at age 31. The obvious historical comparison to make is with other RBs who had a great season at age 28 - let's see what they did at age 31. I found 25 comparable RBs (who had 50+ VBD at age 28, non-ppr, and entered the NFL between 1983 and 2006) - only 32% (8/25) of them were fantasy starters at age 31, and only 8% (2/25) had 50+ VBD at age 31:
Code:
Age31vbd Name Age28vbd
0 Shaun Alexander 221
0 Marshall Faulk 206
26 LaDainian Tomlinson 174
0 Eric Dickerson 154
26 Terry Allen 153
0 Brian Westbrook 147
?? Marshawn Lynch* 144
41 Priest Holmes 142
0 Roger Craig 124
121 Curtis Martin 115
0 Barry Sanders 106
0 Christian Okoye 101
0 Robert Smith 88
0 Jamal Lewis 85
0 Charlie Garner 80
0 Michael Turner 80
0 Earnest Byner 71
0 Thurman Thomas 71
0 Harvey Williams 66
80 Ricky Watters 63
30 Albert Bentley 61
0 Reggie Bush* 59
0 Neal Anderson 54
0 Adrian Murrell 54
19 James Stewart 52
26 Corey Dillon 51
(And none of the guys with 0 VBD at age 31 went on to have positive VBD at age 32+. The only positive VBD season that any of these guys had at age 32+ is Corey Dillon's age 32 season, which was good for 13 VBD.)
The second concern is that it looked like Lynch might have already hit the wall by the time he was 29. His numbers during the 2015 season were way worse than what he had done over his previous 4 seasons in Seattle, and way worse than what Rawls did for Seattle that season: 3.8 YPC on 111 carries, 6.2 YPR on 13 receptions, along with low yardage and TD totals. RBs who have that kind of decline at age 29 usually don't bounce back.