The Rockies upset the Dodgers, 5-2, on Saturday. Prior to that game, the Dodgers were 17-1 at home versus Colorado. It has been 23 games since the Dodgers last dropped two straight games. LA has followed its last three defeats by crushing the opposition by at least five runs each time. 
The price is huge here as it should be with Julio Urias facing Ryan Castellani followed by by Chi Chi Gonzalez as the Rockies are treating this as a bullpen game. So laying 1 1/2 runs on the run line makes plenty of sense.
The Dodgers lead the majors in homers and are No. 2 in runs. They aren't going to lack for offense against these stiff pitchers and Colorado's bullpen. 
LA starter Julio Urias is another one of the Dodgers' high-caliber young pitchers. He's coming off an excellent outing against the Diamondbacks giving up one run on four hits in six innings with no walks and five strikeouts this past Tuesday.