Beltre is still a very good player. Hitting .291/.349/.499 with a 121 wRC+ and rates as one of the top defensive 3rd basemen. At age 37. There's a chance he passes Brooks Robinson (80.2) in fWAR this year. Beltre sits at 79.5, 8th all-time among 3rd basemen.
Even if WAR isn't your cup of tea, there's a pretty good consensus that Beltre is probably one of the greatest defensive 3B of all-time, if not one of the greatest defensive players period. Not only that but his career batting stats are quite good for a 3B (the league average wRC+ at 3B was mostly around 90-100 for the bulk of Beltre's career), especially for someone with so many plate appearances.
It has been a pleasure watching this man in a Texas uniform. He's a HOF without question.
He was in Boston for only one year, but I became a fan very quickly. Glad to see he's lived up to his contract (and some).