The trade deadline is one of baseball’s unofficial holidays, hyped by the league, fueled by its own media cottage industry and viewed as a source of hope for fans across generations.

Old heads might recall such heists like the Atlanta Braves acquiring John Smoltz from Detroit for Doyle Alexander, or the Houston Astros stealing their own Hall of Famer, Jeff Bagwell, from Boston for Larry Andersen.

Younger fans, accustomed to building their own franchises via video games or fantasy leagues, dream on incoming prospects and share with their elders a simple refrain: Better to trade a player than get nothing for them.

Yet increasingly, nothing is exactly what those clubs end up receiving.

A USA TODAY Sports analysis of 94 July trade-deadline deals from 2015 to 2019 that shipped 204 prospects from buyers to sellers confirms a strongly held feeling throughout the industry – that teams are holding their top prospects tighter than ever, making it exceedingly difficult to extract value for star players.

Of the 204 prospects dealt in that five-year span, just 38 have amassed at least 1.0 Wins Above Replacement for the acquiring team. The top five most valuable players traded in that time – pitchers Sean Manaea, Michael Fulmer, Zach Davies, Josh Hader and Matthew Boyd – were dealt in 2015, a year that proved anomalous for many reasons.