Unless you count the Pittsburgh Pirates' trade for Brandon Lowe or the St. Louis Cardinals' multi-part fire sale with the Boston Red Sox, the NL Central has been a sleeping giant all offseason.
The Milwaukee Brewers haven't done much besides extending the qualifying offer to Brandon Woodruff (which he accepted). Ditto for the Cincinnati Reds, who re-signed closer Emilio Pagan and struck out in their pursuit of Kyle Schwarber. And, up until recently, the Chicago Cubs were more concerned with rebuilding their bullpen via the scrapheap than actually improving the team.
But that's all changed now that the Cubs have remembered they're a big-market team within a window of contention.