SAN DIEGO -- The play was still ongoing when Paul Blackburn crumpled to the ground, clearly stunned after taking a high-velocity line drive off his pitching hand. For a long while, Blackburn sat on the slope of the pitcher¡¯s mound, legs splayed, as a group of trainers and coaches checked on him. Eventually, he walked off the field.

Initial X-rays were ¡°inconclusive,¡± according to Mets manager Carlos Mendoza, and Blackburn will undergo further testing on Saturday to make sure nothing is broken.

His early exit in a 7-0 loss to the Padres not only put the team in a difficult position Friday night at Petco Park, but also placed its future rotation plans into question. For all Blackburn¡¯s inconsistencies since headlining the Mets¡¯ Trade Deadline work late last month, he had been a constant source of innings, as durable as anyone.

Now, the Mets can¡¯t be so sure.

How long could Blackburn miss?

The Mets won¡¯t know much until Saturday, when Blackburn undergoes a CT scan in San Diego. That test will determine if any bones are broken.

As a general rule, fractures take about six weeks to heal. Considering Blackburn is dealing with an injury to his pitching hand, it would stand to reason that a broken bone might end his regular season.

If nothing else, screaming line drives can cause plenty of pain, as Blackburn discovered when David Peralta struck him in the third inning of Friday¡¯s game.

¡°It doesn¡¯t feel great, to be honest,¡± Blackburn said immediately after the game. ¡°It¡¯s definitely swollen, definitely some pain in there, but I have full mobility of my wrist and my hand.¡±

If nothing is broken, of course, it¡¯s possible Blackburn could make his next rotation turn. Late Friday night, neither he nor the Mets were willing to speculate on that.

¡°I¡¯m just glad it didn¡¯t hit my head, honestly,¡± Blackburn said. ¡°I just went into defense mode and was able to kind of deflect it.¡±

If Blackburn does miss time, who might replace him?

Although Mendoza said the team has multiple rotation options in the Minors, Tylor Megill profiles as the most obvious one. A frequent rider of the shuttle between Triple-A Syracuse and the Majors, Megill pitched into the eighth inning of his most recent start, striking out 11.

Given top prospect Brandon Sproat¡¯s rocky transition to Triple-A and the season-long inconsistencies of Mike Vasil, Dom Hamel and Blade Tidwell, the Mets don¡¯t have any youngsters knocking loudly on the door. That puts Megill in prime position to take the ball should Blackburn miss time.

Longer-term, rookie Christian Scott may reemerge at some point in September regardless of what happens with Blackburn, Megill or anyone else. Earlier this week, Scott stretched his flat-ground throwing program out to 100-plus feet, while incorporating offspeed pitches into his routine.

The Mets won¡¯t know whether Scott, who has a sprained UCL in his right elbow, can truly avoid surgery until he returns to a mound and begins throwing at full strength again. But they also don¡¯t have any concrete reason to believe Scott will finish this season as anything other than a healthy player.

What¡¯s the state of the rotation in general?

Things had been going relatively well until Friday, when Blackburn allowed 10 hits prior to his injury and recorded only seven outs. Those knocks came in all shapes and sizes, including a Luis Arraez leadoff homer, a Kyle Higashioka two-run shot, and various other line drives and bleeders -- far more support than Padres starter Joe Musgrove needed.

¡°Not good,¡± was how Blackburn put it. ¡°I felt like the good pitches I made got hit. I felt like the bad pitches I made got hit. It was just one of those days where I felt like I was searching for anything to create some swing-and-miss.¡±

Outside of Blackburn, Luis Severino and Sean Manaea have been routinely pitching well, while David Peterson has also found success despite a high walk rate. The outlier has been Jose Quintana and his 8.27 ERA in August, prompting whispers about the Mets finding a way to replace him.

But the depth chart has become noticeably thin, and Blackburn's injury makes the idea of replacing anyone that much more difficult.

Said Mendoza, when asked about potential Blackburn replacements: ¡°It¡¯s too early to tell.¡±