The first thing you need to know about Seattle is that their defense is ridiculous this year. Franklin Gutierrez, Endy Chavez, and Ichiro form a superb defensive outfield, and as such, the Mariner pitchers are having a good start to the season. Combine their defense with the ballpark -- unkind to right-handed power -- and it could become a trying series offensively. The good news is, the Rays pitching should get a break from the onslaught of difficult offenses.
Washburn has a .203 BABIP and a strand rate nearing 95%. He's only missing marginally more bats and his flyball/line drive rates have remained steady. Throw in nearly zero difference in stuff and pitch usage - although he has used his fastball more and slider less - and it's difficult seeing Washburn being anything but the benefactor of the improved glovework. Washburn is a soft tossing lefty without an out pitch and with the tendency to allow homeruns. That means expect a career performance.
Jakubauskas is filling in for the injured Ryan Rowland-Smith. His minor league numbers are nice, although there's been some debate as to whether Jakubauskas can succeed with his stuff. Fastball in the low-90s, curveball and change; a rather rudimentary arsenal.
Finally, Felix. He throws in the mid-90s but can pump it up when needed. Look for a fastball heavy attack, with some sliders, curves, and changes tossed in for good measure. Felix doesn't walk a lot of batters nor does he give up many homeruns anymore, and if this improvement in strikeout rate is legitimate, then you're looking at a legitimate Cy Young contender. If you don't think you'll make it home by 6:40 Thursday night, take off early, Shields and Hernandez should be delightful.
You may remember Johnson from the Al Reyes rumors a while back, he's filling in for the injured Kenji Johjima and exiled Jeff Clement - who you may recall from the Edwin Jackson rumors. Branyan was mildly entertaining in his 2006 stint with the Rays as the all-or-nothing slugger. Beltre is Longoria's biggest hurdle to becoming the best third baseman defensively in the A.L. Betancourt is the rather large shell of his former self - the defensive wunderkind who frustrated the heck out of the Rays.