Oakland Athletics (18-21, third in the AL West) vs. Seattle Mariners (20-18, second in the AL West)Seattle; Friday, 9:40 p.m. EDTPITCHING PROBABLES: Athletics: Paul Blackburn (3-1, 3.00 ERA, 1.02 WHIP, 31 strikeouts); Mariners: Bryan Woo (0-0)BETMGM SPORTSBOOK: LINE Mariners -145, Athletics +122; over/under is 7 1/2 runsBOTTOM LINE: The Seattle Mariners host the Oakland Athletics on Friday to open a three-game series.Seattle has a 20-18 record overall and an 11-8 record at home. The Mariners hav