As the saying goes, you can never have too many defensemen in your system over the course of and NHL season.
That being said, there is such a thing as having too much of a certain type of defenseman. Ottawa has an abundance of puck movers in their system, from Erik Karlsson on down to Chris Wideman. Including Cody Ceci and Patrick Weircioch in that group and there probably isn't enough room for them all on the roster at the same time.
Ceci is developing into a very good two way blueliner who has probably shown more in his own end than most would have expected at this point in his career. His point production will improve as he becomes more comfortable, and he has the potential to be a very good two-way defender and legitimate 2nd pair defenseman.
Karlsson's role with the club is well known. His best attributes are with the puck, and offensively he is the catalyst of the club.
That leaves Wiercioch and Wideman. Is there room on the Senators' blue line for both of them? A club needs some balance, and I am not sure there is room for two more offensive minded defensemen who aren't noted to be very adept defensively on the bottom two pairs.
Complain as you did about Gryba and Cowen and their level of play, but you need that type of defenseman in your lineup as well if you are going to succeed.
If the Senators were to deploy a blue line of Karlsson, Methot, Ceci, Wiercioch, Borowiecki and Wideman, who will kill penalties? Karlsson doesn't need the extra workload and would you want Wideman or Wiercioch on the PK? I haven't seen Wideman play and I don't know for sure, but judging from scouting reports he is a battler but his size (or lack thereof) will make penalty killing in the NHL a tough go.
Wideman's best attribute is on the power play, and he might be the answer to finding someone to play opposite Karlsson with the man advantage, either on the first or second unit. But if he gets that spot, is there a reason to dress Wiercioch, who should essentially fill that same role?
And this is all a conversation that hasn't included Jared Cowen, Chris Phillips or Frederik Claesson, two of whom are pretty much guaranteed roster spots for the coming year and another who was the captain in Binghamton at age 21 and is also pushing for an NHL shot.
People look at the stats Wideman put up last season and, while impressive, are not the be all, end all for making the NHL, especially when similar situational opportunities are not available to the player. You just have to look at the much traveled T.J. Brennan to see that points in the AHL do not equate to full time NHL employment.
Having an abundance of NHL level defensemen is a good problem for most teams to have, but I can imagine is pretty frustrating for those players that are on the cusp but being held back because of contracts ahead of them. Wideman will probably get a chance this year, but might have to bide his time until the right opportunity presents itself, because the Senators will have multiple options if and when a defenseman goes down to injury, regardless of how they line up on opening night.