Reminder: Always double check the lineup card before rosters lock to make sure that a player you've chosen to roster is playing that day, and check the weather to make sure your players won't get rained out of their game.
Rockies stack vs Jason Marquis in Great American Ballpark
Marquis has been one of the least effective pitchers in baseball over the last 4 seasons. In 287 IP since the start of 2012, Marquis owns a 4.99 ERA (8th worst) and 5.35 FIP (worst). Key Rockies hitters have had shockingly poor results vs RHP to start the year, which has created a lot of potential surplus value in this matchup.
Updated 11:00 am: Tulowitzki and Blackmon are not in today's lineup
Troy Tulowitzki, $3,900
Troy Tulowitzki's 57 wRC+ vs RHP is unbelievably bad, especially because it comes with a .287 BABIP. Here's reason for hope with Tulo, though: he is ending about 20% of his at bats against RHP with a hard hit ball. That is well above the MLB average of about 15%, and if he keeps that up, good results are going to start coming. Tulo's % of ABs with a hard hit ball vs RHP is 3rd best among MLB SS in 2015, so he has not performed as badly as his outcomes lead you to believe. His HR/FB rate has dropped to just 2.7% against RHP (career 14.7%), which probably explains a lot of his power outage, especially because he is still hitting the ball hard at a well above average clip. Tulo's nosediving walk rate is a major problem, and an increase in his swing and miss is also alarming, but I don't think hitting for power will be an issue going forward.
Carlos Gonzalez, $2,900
I keep hammering CarGo into my daily lineup because of his price drop and it hasn't worked out yet, but I still believe in him. The primary reason for that is because he's among MLB's best in exit velocity off the bat vs RHP, which shows that he still has high level force behind his swing. CarGo's average exit velocity vs RHP is just over 94 mph, 9th best in baseball among hitters with 50+ BIP. It appears CarGo's problem has mostly been poor trajectories, as his hard hit rate vs RHP, which combines exit velocity and trajectory, is 16.7%, 109th overall. When a hitter is generating a lot of exit velocity off the bat but is hitting into poor trajectories (for example: jamming the ball into the ground off the bat), that makes me think he's just a little bit off. CarGo missed a lot of time last year with knee and finger injuries, so it's possible he's still regaining timing at the plate. I'm all aboard the Cargo train at sub $3,000 prices because I believe in much better days ahead.
Nolan Arenado, $3,200
Arenado is ending 21% of his at bats vs RHP with a hard hit ball, 19th best in baseball and best among Rockies regulars. His .254 ISO vs RHP is 3rd best among MLB 3B, and that isn't a product of Coors Field, either, because Arenado actually has a higher ISO vs RHP on the road (.371) than at home (.115). Arenado is the 9th priced 3B today, and the poor opposing pitcher + excellent hitter's ballpark makes him a strong play.
Charlie Blackmon, $3,500
Blackmon has been Colorado's leadoff hitter, which is valuable in a matchup against Marquis where you want to get as many cracks at subpar pitching as possible. Blackmon has had the best results of the stack vs RHP by wRC+ this year, posting a 127 wRC+ with a .196 ISO. Most of Blackmon's value in fantasy comes at home in Coors Field, but Great American Ballpark is a fantastic park for LHB: it's been the 4th most HR friendly park for LHB the last 5 years according to FanGraphs' park factor calculation.
Follow me on Twitter at @TimFinn521, I usually tweet out more good options as lineups are released.