I think it is time we had a true PF that can compliment Drummond. Monroe is about to be due a max deal, and do you really feel like he is worth that max, especially compared to the guys I named? Monroe is a below average defender who will be, at best, a 15/9 guy. We maximized his talent, now it is time to cash in.
Another guy that would be a darkhorse to go after is Derrick Favors. If given starter minutes, he could give us 15/10 as well as 2+ blocks/1+ stl a game, as well as real defense. He is a legit PF too. Not sure how his jumper will be, but it is probably as good as Monroe's now. He is also a year younger and we could probably lock him up for a lot cheaper than Monroe will cost.
Before I get attacked for mentioning trading Monroe for Favors/others, look at how they compare.
Basketball Reference: Monroe v. Favors comparison link
Monroe may be the better overall offensive player, especially when considering his passing, but Favors is a considerably better defender. One that could be on an All-NBA Defensive team good. As mentioned earlier, Monroe is a huge liability on D.