The height and reach advantage of Jacobs was a little too much to overcome. I also think that Jacobs knew what he had as they have sparred for years together, it looked like he Jacobs ready to go at one point in the 12th round but his tank was near empty at that point.
Sergey usually overcomes opponents with his quickness, but he couldn't get to Jacobs like he's done with most of the others. Jacobs did seem like he knew what to expect. It was a good, competitive fight, very close. A couple of rounds could have made the difference.