Now, had Mark Appel somehow slid to the Phillies, the Tyler Cloyds, John Lannans and Jon Pettibones of the Phillies universe might have a legitimate worry. Appel could honestly jump right into the Astros rotation tomorrow and be a pretty solid starter. At most he'll spend a year and half in the Minors. That's quick, much quicker than most prospects. If JP Crawford is taking Rollins' job, it's only in the same way Charlie Hayes and Dave Hollins took Mike Schmidt's. By the time Crawford makes it to even Double-A, Rollins may well be sitting in Studio 42 analyzing games and players with all of the other former Phillies on the payroll.
Crawford is no more of a threat to Freddy Galvis, Roman Quinn or Edgar Duran. Much has been made of Quinn's struggles at Shortstop, and there have been plenty of them. Quinn has great speed and plenty of arm for Shortstop. What he doesn't have is any experience at the position. Think about what Quinn is doing, and it's pretty impressive, He's learning to hit Left Handed, he learning to play the second most difficult position in the game and he's learning to adjust to professional Pitching all at the same time. That's pretty damned tough and the kid's doing it well enough to get ranked as a top 5 Phillies Prospect by virtually every prospect expert in the country. Shortstop is a tough position. No one is going to master it in 1 year and you'd have to be very elite to master it in less than 2. Quinn may never master the position, that's perfectly reasonable to assume. What we know about Quinn is that he was seen as a likely plus Defender in Center Field in High School. He can probably move to Center and from day 1 handle it fine. We also know that Quinn is probably, at minimum another 2-3 years from playing in Philly. So there's no need to move him from Short now, move him in 2 or 3 years if it's clear he won't stay there.
JP Crawford, once he signs, will probably be the Starting Shortstop for the Williamsport Crosscutters. He'll move to Lakewood in 2014, as Quinn moves to Clearwater. In 2015 Quinn will try his hand at Reading, while Crawford goes to Clearwater. Neither one blocks the other. Neither one forces the other to move or be traded or anything else.
Another important point to remember is that while Crawford already plays Shortstop, that is no guarantee that's his long term home. Crawford positions himself well and probably has enough arm for Third base. He doesn't go to his right very well yet and, at 6'2" he's on the tall side for a Shortstop and could eventually grow into a Third baseman or Center/Right Fielder. Now, you move Quinn off Shortstop and 3 years down the line you might find them blocking each other in Center field instead.
Similarly, Andrew Knapp is little to no threat to Tommy Joseph. Joseph will likely be in Philly sometime in 2014. Even in the best case scenario, Knapp won't be in Philly until 2015. Even in that case, we don't know if Knapp can stick at Catcher Defensively. A more likely timeline for Knapp to make the Phillies as a Catcher would probably get him to the show in ~2017. By that time Joseph is either well established as a Phillies Starter and Knapp or Joseph become tradeable. Or Joseph has struggled and Knapp gets a chance to start in 2018. Prospect development cycles are long and unpredictable. Jayson Werth was drafted as a Catcher and is now an All Star Right Fielder. Chace Numata was drafted as a Shortstop and Outfielder and is now being developed as a Catcher. Positions listed on Draft trackers for MLB prospects are more often informational than projections. For example, Justin Williams was selected right before Knapp in the Second and was listed as a Shortstop. I'm not sure any prospect experts think Williams can stick at Short, he's an Outfielder, but he played some Short in High School, so there you go.
Now, there is one person (perhaps two) who might be affected by Knapp's selection and they're both in Double-A. Knapp is a more advanced hitter than Cameron Rupp (who's a better Defender when he was picked) and shares a similar ceiling as a backup/fringe starter. Similarly Sebastian Valle has seen his stock plummet the past 2 years and a change of scenery may help. Both could be tradeable, and frankly one probably should be traded to allow both to get regular playing time to develop to their ceilings. I'll be honest here, this theoretical trade would be just as likely without Knapp in-house, but with Knapp you now have a clear succession plan to replace the traded player's talent.
Just remember as you watch the Draft's next 8 rounds today that each prospect is developed in a virtual vacuum until they get to Double-A or Triple-A and being blocked at the MLB level becomes a realistic concern. And, mostly, don't read too much into picks. The fact that the Phillies liked a certain kid enough to draft him doesn't mean they dislike or have doubts about someone they already have. There's plenty of room at the table... for now.