Looking at RPI, Oregon State is currently fifth. The Trojans are a better RPI team than the Cougars, so the Beavers should gain on the Cardinal, if they finish with at least the same record. Stanford probably stays ahead of Oregon State with a series win. The Beavers probably pass the Cardinal with a sweep and a Cougar series win. If Washington State sweeps Stanford, the Beavers probably pass the Cardinal, absent a Trojan sweep.
#3 in RPI Arkansas and #4 in RPI Georgia play each other this weekend. It is probably not possible for the Beavers to catch the Razorbacks. Oregon State can probably pass Georgia with a sweep and a loss by the Bulldogs. If Georgia loses two, Oregon State probably passes the Bulldogs, absent a Trojan sweep.
#6 in RPI North Carolina lost their midweek game to UNCW and are playing RPI-poison Virginia Tech. If the Tarheels win the finale, they could probably pass the Beavers, if the Trojans win the series. If the Tarheels lose the finale, they can probably only pass the Beavers with a Trojan sweep.
#7 in RPI Stetson is playing RPI-poison South Carolina Upstate. If Stetson sweeps South Carolina Upstate, they could probably pass the Beavers, if the Trojans win the series. Oregon State probably stays ahead of Stetson otherwise.
#8 in RPI Ole Miss is playing Alabama. If the Rebels sweep the Tide, they could probably pass the Beavers, if the Trojans win the series. If the Rebels and Tide split the last two games, Oregon State probably stays ahead of Ole Miss, absent a USC sweep. If the Tide win the series, the Beavers probably stay ahead of the Rebels.
#9 in RPI Texas Tech is playing Oklahoma State. If the Raiders sweep the Cowboys, they could probably pass the Beavers, if Oregon State fails to sweep USC. If the Cowboys and Raiders split, Texas Tech probably passes Oregon State with a USC series win. If the Cowboys win the last two, Texas Tech can probably pass Oregon State with a USC sweep.
#10 in RPI Florida State is playing NC State. Oregon State probably stays ahead of Florida State with a sweep. If the Beavers falter once or twice, Florida State probably passes Oregon State with a sweep. With a Trojan sweep, Florida State probably passes Oregon State with a series win.
#11 in RPI Clemson is playing Pittsburgh. The Tigers need a sweep and a Trojan sweep. Otherwise, Oregon State probably remains ahead.
#12 in RPI Auburn is playing LSU. The Tigers need a sweep and a Trojan sweep. Otherwise, Oregon State probably remains ahead.
Nobody else seems in range of Oregon State. It is possible for Oregon State to finish #3-#12 in RPI after this weekend.
At this point, it would be very surprising to see Oregon State not host a Regional. Oregon State probably earns a National Seed with a 4-2 finish, if the wins and losses fall the right way.