5. Travis d'Arnaud
Travis d'Arnaud was always a highly touted prospect upon being drafted by the Phillies in 2007. He was dealt twice for Cy Young Award winners before making his debut with the Mets in 2013; Roy Halladay and R.A. Dickey. These blockbuster trade deals made d'Arnaud a blue-chip prospect with 'Mike Piazza' power at the plate. His defense was a question mark, even as a young prospect but he handled pitching staffs well and was a great pitch framer.
d'Arnaud never lived up to the hype of being acquired for R.A. Dickey; in fact, we remember this trade more as the Noah Syndergaard trade than the d'Arnaud. He was demoted early on in 2014 for poor performance, but bounced back nicely in the second half, earning himself the starting role in 2015. d'Arnaud only played in 67 games in 2015 due to injury but played his best baseball as a Met during this stretch including 3 postseason home runs.
d'Arnaud may be the most frustrating player in Mets history. Outside of his struggles in 2016, d'Arnaud always hit the ball well and was an asset for a young pitching staff. He struggled to throw out base stealers, though I would put more blame on the pitchers themselves given Mesoraco, Plawecki, Ramos, and Rivera couldn't throw anyone out either. Most Mets fans never embraced d'Arnaud because of the Mike Piazza expectation set on him in 2013. Speaking personally, I always liked d'Arnaud and felt that expectation was unfair. Since signing with the Braves in 2020, d'Arnaud has become another Met-killer just like Daniel Murphy and Justin Turner.