For what it's worth, ZiPS projects 2018 WAR of 0.9 in 405 plate appearances for Rusney Castillo and 2.0 in 354 plate appearances for Jarrod Dyson.
https://www.fangraphs.com/blogs/2018-zips-projections-boston-red-sox/
https://www.fangraphs.com/blogs/2018-zips-projections-seattle-mariners/
Steamer600, which assumes 600 plate appearances for each outfielder, projects 2018 WAR of a negative 0.7 for Castillo and 2.3 for Dyson.
https://www.fangraphs.com/projections.aspx?pos=all&stats=bat&type=steamer600&team=3&lg=all&players=0&sort=27%2cd
https://www.fangraphs.com/projections.aspx?pos=of&stats=bat&type=steamer600&team=0&lg=all&players=0&sort=27%2cd