That's kind of apples and oranges though, when was the last time Saudi Arabia fought a land conflict on a scale like this? It's not unreasonable for a technical force with a lack of experience to have issues against a force like in Yemen which is equipped with semi-modern equipment and at least some combat experience running over the current government.
Whereas in the air they have total superemacy, there is no contest and there never was. They can strike with impunity and as have the capability to root out those missiles and destroy them thanks to the equipment they use. You're right, it is incompetence, it's just the sheer magnitude of it in the face of what kit they have I find unbelievable.
And who's to say some of Soliemani's Quds aren't there advising and likely fighting with the Houthis. There are numerous accounts the CGC is facing experienced Guds and Houzballa fighters as well as battle tested Houthis
Estimates put the number of both Iranian and Iraqi Shi’ite forces helping the Houthis in Yemen at around 5,000 people. The number of Lebanese Hezbollah members in Yemen is not known.
On Sunday, Quds Force Deputy Commander, Brig. Gen. Esmail Ghani was quoted as confirming the fact that the IRGC is training Yemenis.
“Each one who is with us comes under the banner of the Islamic Republic and this is our strength,” Ghani said, according to Iran’s Mashregh News, an outlet run by the IRGC. “The defenders of Yemen have been trained under the banner of the Islamic Republic and the enemies cannot deal with Yemeni fighters.”
It was the first official reference to Iran’s training of the Houthis in Yemen.
According to several officials, the ultimate goal of the Iranians in Yemen is to control the Red Sea chokepoint of the Bab-el-Mandeb.
“The Iranians’ ultimate target is the strait [Bab-el-Mandeb] and the House of Saud is the other target,” one official said.
The Bab-el-Mandeb is a strategic chokepoint that could be used by Iran to block oil shipments and U.S. warship movements from the Mediterranean to the Indian Ocean and Persian Gulf. Iran already can threaten the region’s other strategic chokepoint, the Strait of Hormuz in the Persian Gulf.
Control over the Bab-el-Mandeb would give Tehran additional regional power to control oil and other passage to and from the region.
Houthi military plans and operation are “completely under the supervision and control of the Quds Force,” Gobadi added.
IRGC Maj. Gen. Qassem Soleimani, the Quds Force commander, directs several special committees to back the Houthis, according to Gobadi. Some 50 tons of Iranian weapons and other aid was sent from Mehrabad airport in Tehran to Sanaa last march March in four shipments, Gobadi said, noting the shipments were disguised as humanitarian aid from the Iranian Red Crescent.
So my take is the obvious here, the GCC is not getting dismantled simply by the Houthis but the IRCG and experienced Houzballa fighters
U.S. Intelligence: Iran Sending More Fighters to Yemen