The Cubs bullpen needs a lot of work, and they'll need to add multiple experienced arms before Spring Training. One name on the free agent board is former Cubs closer David Robertson. The veteran righty recorded 14 saves and pitched to a 2.23 ERA and 1.04 WHIP in 36 appearances for the Cubs in 2022 before being traded to the Phillies for Ben Brown.
Last season between the Mets and Marlins he pitched to a 3.03 ERA, 3.55 FIP, 1.19 WHIP, 10.7 K/9, and 3.4 BB/9 in 62 appearances. He was still throwing his cutter, his primary pitch, 93-94 MPH along with the knuckle curve, slider, and an occasional changeup. Per BaseballSavant he was above the 80th percentile in Whiff rate (85th), K rate (86), xERA (87), and xBA (90) and was in the 74th percentile in Pitching Run-Value. Robertson's cutter was a +11.8 value per FanGraphs and was among the leaders in Stuff+ (125) among relievers last year.
To sum it up, he put up some good numbers in the box score overall and it was not necessarily a fluke. His cutter has helped him succeed later in his career and he was still effective at missing bats last season.
Robertson is 38 years old, and there is a risk adding an aging arm like that for a big role. Though he does not necessarily have to be a closer. The experience he brings could be valuable if he can still pitch to a high-2.00/low-3.00 ERA and mid-3.00 FIP. Considering over his last two seasons he posted a 3.58 FIP in 2022 and 3.55 FIP in 2023 so he's been consistent since he came back from injury full-time (he pitched only 18.2 innings from 2019-2021). The Cubs in 2022 were the team for which he pitched 40+ innings for the first time since 2018
Robertson signed a 1-year, 10 million deal last year with the Mets. Per Spotrac, his market value is roughly at a $8.9 million annual salary. A potential deal is likely either a one or two-year deal.