First of all, warhead designs, are application specific.
I am sure this launcher called the BUK can accommodate several types of missiles, usually at least 2-3 variants.
We really don’t know what warhead design it had so I am going by the damages I see and have seen in days of picture releases.
As to continuous rods, I understand the concept and have actually seen it in frag weapons of the 1960’s, but in these the rods were either cast or had score marks to break them up in whatever size was required.
In the case of a anti-personnel weapon, the rods and it’s fragments would be smaller. in the case of a aircraft they would be sized to the most effective mass and size for the required effective burst area. Never seen the guts of one, but It seems likely the frag size would be equivalent to the size of the most effective AA ordinance which is 20mm-30mm in diameter.
When designing this stuff you have to take into consideration the flight characteristics of the fragment to make it as effective as possible..(rarely miss) and to do that you need a fragment that flies true, like a ball or something that is just as wide as it is long, which approximates a ball or a chunk with a balanced dimensions.
I use the term ball, because that works as do aerodynamic chunks, which we use in many of our frag weapons.
The effective area of a AA warhead burst can be in the neighborhood of 200-300 sq meters and continuous rods without fragmentation shear points to create (chunks or ball like projectiles) will not give you that sort of effective range. In my experience the rods type, usually copper, was a anti tank or anti bunker warhead. The rod is designed to melt and burn it’s way through, which is why calling the Buk oridinance a rod type can be somewhat misleading.
I would draw one for you, but I can even post a picture if I had one, but the fragment resembles a ball and has beveled edges.
In some applications, prior to fragmentation it may look like a bunch of rods that are twisted like a steel cable.
But after fragmentation they look closer to little 10-30mm balls or chunks ...
All the Buk missile variants have a blast fragmentation warhead. There’s a companion vehicle optimized for smaller and more agile targets that is often deployed with Buk systems called the Tunguska that does carry a CR warhead, though.