A viable play even before Johnson was ruled out, Riddick gets a boost this week as well. Blount is a total non-factor in the passing game, having seen only five targets on the year and averaging at least one target per game in only one of his nine seasons in the NFL.
Johnson, while not always a target hog in the passing game, saw at least five in three of his last four games, averaging 5.5 per game in that stretch as well as 4.0 per game on the season.
Riddick has seen at least seven targets in each of his last three games, and at this point has been functioning more as a wideout than a running back, with only one carry in those last three games. Johnson's absence may lead to a bit more rushing work for Riddick, giving him even more fantasy value, while his floor for passing game usage is very safe.
Targets are worth about twice as much as carries, as far as expected fantasy value goes, and that means that even though Riddick may not see a huge number of overall opportunities, he can still offer both a solid floor and ceiling thanks to the pass-heavy nature of his volume.