Jerry DiPoto (Angels GM)
2012.... 89 - 73 (0.549)
2013.... 78 - 84 (0.481)
2014.... 98 - 64 (0.605) * Won AL West Division
2015.... 85 - 77 (0.525) (and Stoneman as GM... DiPoto quit halfway through the season b/c Moreno didn't back up the GM)
Billy Eppler (Angels GM)
2016.... 74 - 88 (0.457)
2017.... 80 - 82 (0.494)
2018.... 80 - 82 (0.494)
Eppler took over a team that was posting over .500 record for three out of four seasons under DiPoto.
Jerry DiPoto (Mariners GM)
2016.... 86 - 76 (0.531)
2017.... 78 - 84 (0.481)
2018.... 89 - 73 (0.549)
In that same span, DiPoto posted over .500 twice with the Mariners. In 2015, the Mariners posted a below 0.500 season.
The farm system was bare when DiPoto became GM. When owner Moreno wanted to sign FA 1B Pujols, it cost the Angels a first round pick. That same year, Dipoto traded for starting pitcher Greinke. Dipoto probably wanted retain Greinke (b/c he gave up valuable assets to acquire Greinke) after the season ended. Instead, owner Moreno stepped in again and wanted free agent outfield slugger Hamilton. Hamilton cost the Angels another first round pick. That was a terrible transaction and revealed how an owner can set back the organization years by stealing away a first round pick two years in a row.
Under Dipoto, he made a concerted effort in replenishing the farm with pitchers or trading for young pitchers.
With Eppler, he went a different direction. He opted for offense and defense over pitching.
Eppler traded a plethora of young pitchers for assets for his current team. Simba (Simmons), Upton, and Ohtani paired with Trout, one would believe they would perform better. Eppler's way hasn't netted a .500 team under his 3-year tenure. There is no way you can say that Eppler performed better than a DiPoto management with the Angels as of yet. Now, compare each GM with their respective teams from 2016 - present. DiPoto still wins in that 3-year set. I don't know what other excuses you want to put up, but Eppler inherited an above .500 team.
As for what Eppler has planned for the Angels this winter... welp, a bunch of small things. Here's a link to some tweets that confirms so:
The Angels have gone from going for a touchdown to being "off the football field", per Billy Eppler
Eppler has accrued some great talent in Simba and Ohtani along with good talent in Upton. Yet, Dipoto still reigns supreme. Remember, Eppler needed assets to land Simba and other talents. So let's end this lie that DiPoto left Eppler with nothing. In three years under Eppler, we're still far away from putting up a competent whole team to go over .500, let alone a playoff team to that of 2014.