Bruce Irvin gives Raiders bookend pass-rusher with All-Pro Khalil Mack

ALAMEDA, Calif. -- The Oakland Raiders are apparently not playing around in free agency this time around.

And their defense is about to get a little more fierce.

Agreeing to terms with free-agent linebacker Bruce Irvin, who spent the first four years of his career with the Seattle Seahawks, gives the Raiders a bookend pass-rusher to go with All-Pro Khalil Mack.

Of course, the signing cannot become official until Wednesday at 4 p.m. ET, when the new league year begins.

And we have yet to even think about the Raiders' purported chase of Aldon Smith, who cannot be re-signed until his year-long suspension is up in November.

Yes, on paper at least, Oakland's pass rush should be fearsome, especially in nickel packages.

The 6-foot-3, 260-pound Irvin, who was the No. 15 overall pick of the 2012 draft out of West Virginia, has 22 career sacks (5.5 last season) and has started 37 of his 58 career games.

In Seattle he made the conversion from defensive end to outside linebacker under the tutelage of Ken Norton Jr., who is now the Raiders' defensive coordinator. Irvin can play both standing up as a strong-side linebacker in base defense and with a hand in the grass as the right defensive end in nickel coverage.

That should pair well with the ultra-versatile Mack, an All-Pro who played at both linebacker and defensive end after racking up 15 sacks last season, with five coming against the eventual Super Bowl champion Denver Broncos in December.

Plus, Irvin, 28, coming to Oakland will set up a homecoming with another former Seahawks teammate in middle linebacker Malcolm Smith, who signed with the Raiders last offseason.

Earlier in the day, the Raiders, who entered the day with more than $63.5 million in salary cap space, agreed to terms with one of free agency's most sought-after offensive lineman in former Baltimore Ravens left guard/left tackle Kelechi Osemele.