Kyle Schwarber is ranked 18th among outfielders
We all know the deal with Schwarber, as he absolutely mashes but can cripple your team's batting average. This is especially true since he'll probably hit leadoff again and amass a large number of plate appearances on the season that you'll find difficult to offset with higher-average guys on your fantasy squad. But he's a known commodity that you have to plan around, and you always pay a premium for guys who hit in stacked lineups like the Phillies seem to have.
I think 18th is a tad high, but appropriate. Frank Stampfl has him 21st, which is probably the sweet spot. If your league uses OBP instead of batting average, Schwarber doesn't sink you as much.
Nick Castellanos is ranked 25th among outfielders
I think Castellanos is accurately slotted here, well back of the true stars and hyped-up younger players but ahead of some other guys who don't have his track record. He's another one of those "boring" veterans at this point, but he makes a great OF3 for your club. You know what you're getting. At the same time, nobody's heart will be broken if Castellanos gets sniped one pick before their turn.
Whit Merrifield is ranked 61st among outfielders (and 24th among second basemen)
Whit Merrifield presents an interesting case, as it'll all come down to playing time. Can he get enough of it to steal 20+ bases and for his typically good average to make a dent on your roster? He makes for a decent gamble in your middle infield slot or a bench bat. If you're actually drafting him as one of your regular outfielders, though, you're in trouble. You're better off going with a more unproven player who will at least be given a starting spot out of the gate to show what he can do.
Brandon Marsh is ranked 90th among outfielders
I think this is a low number for Marsh, but it's also probably reflective of health concerns after his surprise offseason surgery put the start of his season into question. So I can't grumble too much about that, but this is one that I fully expect to look foolish by season's end. If he plays 140+ games, Marsh should be able to put up numbers more in line with the guys who are being ranked in OF slots 60-75. In fact, I will say the same about Johan Rojas, who didn't even crack the top 100 in CBS' projections.