It really isn't that easy to find a good OF though. Amazingly Kepler may have actually been the best off-season free agent signing, relative to term and cost, even if the Phillies had been willing to dish out money and years. Of the Top 50 MLBTR guys Santander, Profar, O'Neill and Joc Pedersen all busts. Teoscar Hernandez wasn't leaving LA and isn't a strong defender (even if he's better than Nick). Harrison Bader (who was 49th) would have been okay (leaving Marsh in LF). Randall Grichuck (an honorable mention along with Kepler) might have been a better fit as a righty but we passed on him twice in 2023 and he has a 0.0 WAR.
Juan Soto's good of course. And so is Kyle Tucker. But neither of them were available at an acceptable price (money in the former case, players in the latter). They've been correct to stay away from Robert too.
In the end individual stats and individual WAR don't matter. Marsh has put his poor start behind him and will be the equivalent of a 2.0 WAR player, if not more, from May onwards it seems. Hopefully Kepler, coming off an injury and changing teams, will turn it around as well. Casty can hit and was never supposed to play RF. The roster is still poorly designed in terms of there being too many DHs and one too many LHBs, plus a catcher who is paid to hit like a top bat and isn't anymore.
I'd be all for finding a new everyday LF at the deadline but that probably costs you Crawford or two Top 10 guys who aren't him in a vacuum, if that player even exists. They won't do that. They'll keep looking to improve the bench or platoon situation.
Even the two spots where they could make a surprise dramatic change can't really be addressed easily. You don't really want to move on from Bohm (since he's hitting) or Stott (still a good 2B) yet IMO but even if you did only limited upgrades are out there. Leaguewide, 2B is as weak as OF right now. And of course five or even 10 other teams all want the same thing the Phillies do, including the Mets (CF and closer-type arm).