W2W4: Rangers at Mariners

ARLINGTON, Texas -- The Rangers make their first visit to the Pacific Northwest for a four-game series against AL West Division rival Seattle.

The Rangers have opened the season winning their first three series, winning two out of three from Houston, the Angels and Tampa Bay. They lost two of their three series in Seattle last year and finished 4-5 at Safeco Field. The Mariners are 4-6 and in third place in the AL West behind Oakland (7-2) and the Rangers (6-3).

Here's what to watch for in this Thursday-Sunday series:

Felix's fastball: Mariners ace Felix Hernandez, who goes for his 100th career victory Thursday night, has been one of the best power starting pitchers in baseball. But his fastball velocity has dropped from an average of 94 mph in 2009 to 89.7 mph so far in 2013. He threw 59 fastballs in his last start with an average velocity of 88.6 mph, two mph slower than any start in his career. Hernandez is off to a 1-1 start with a 2.57 ERA. He has 11 strikeouts in 14 innings.

The power of Morse: New Seattle left fielder Michael Morse is one of the best unknown power hitters in baseball. Coming over from the Washington Nationals, Morse already has six home runs in 38 at-bats. He is tied for the major league lead in home runs with Atlanta's Justin Upton. Morse has nine RBIs, tied for sixth in the AL, and is batting .263 with 11 strikeouts and has drawn one walk.

Mariners struggle with injuries, Astros: Mariners outfielder Michael Saunders sprained his right shoulder trying to make a lunging catch at the right-field wall Wednesday and is expected to miss some time and maybe go on the disabled list. That was one moment in an awful home series against the Astros, who beat the Mariners again Wednesday, 8-3. Seattle was outscored 24-12 in the two games against struggling Houston. The Astros racked up 37 hits against Seattle pitching.

Darvish's Seattle struggles: Yu Darvish was 0-2 with a 9.58 in two starts last season at Safeco Field, one of three ballparks he struggled in (the Oakland Coliseum and Boston's Fenway Park were the others). Darvish allowed 12 hits in 10 1/3 innings in Seattle, but he had 10 walks against only nine strikeouts.

Rangers domination: Despite going 4-5 last season in Seattle, the Rangers are 17-11 in Seattle since 2011. They are 37-20 against the Mariners in the last three years, a big reason why the Rangers have made three consecutive playoff appearances. The Rangers have won the season series in eight of the last nine years.