Russell Wilson giving 49ers’ defense fits in first half

Early in the second quarter of Thursday night’s matchup vs. Seattle, the 49ers got an object lesson in the dangers of blitzing Seahawks quarterback Russell Wilson. On a 3rd-and-9 play, Wilson spun away from onrushing 49ers defensive back Dontae Johnson, cut back to his right, avoided tackle attempts from Johnson and linebacker Chris Borland and…