I think they were still hoping he could turn it around though, or they just genuinely wanted the depth. He was stringing together 3-4 decent outings with one epically bad one and wasn't necessarily worse than the guys in AAA. Now it just looks stupid that they lost Lazar for 15 days. But the fact that they are even hinting at an IL stint shows they aren't fully committed to cutting him loose. What they should really do is see if he'd take an optional assignment w/o the DFA.
The timing was different with Merrifield, that was July 12 and the Phillies knew he'd catch on with another team. With Romano they only had to wait six more days to make it less attractive for another team to sign him (or for him to sign with another team). If he's hiding an injury or if his arm is shot it might not matter, but with a reliever, more than a bench player, it's easier to imagine him still signing with a relief-desperate team (which is still most of them) and being useful. Just not too easy, at this point.
The Phillies also released Merrifield. No DFA. They could do Romano that courtesy too if they want him to get another chance somewhere.