This is the second time I've run into this problem this season. The first time was early in the year with Drew Smyly, who wasn't added until the day of his start. Supposedly the problem had to do with him not being on the 40-man roster.
But Grimm's start was announced four days ago, he pitched Saturday, and as of midnight he is still nowhere in the system. I can't think of any reason he couldn't have been added as soon as he was put on the Rangers' 40-man roster today.
This is a major, major problem in deep leagues such as the one I run. Smyly and Grimm are small fry for mixed leaguers but in deep leagues they are important. I'm not in the habit of complaining about a service I get for free but that's a major fail.
Already half my league wants to switch to a four-letter service provider but I've stuck by Yahoo. Next year will probably be different, sadly.