Lucretia, along with Shu to some degree and definetly Albert Silverberg, are so utterly flawless as strategist that they can all be considered Mary Tzu's
in their own right. It's kind of hard to compete with some characters who pull off some of the craziest and convulated plans ever and have some kind of major contingency plan for any kind of set-back no matter how random or out of nowhere it can be.
While I can agree Mathiu Silverberg is an underwhelming strategist compared to some of the other strategist from later games, I don't feel any of the TC's arguments hold as being bad:
1)Taking Toran Castle as an HQ
Not a bad idea really, of anything the real question people should be asking is why the Empire didn't send Sonya to take care of them in the first place? I mean Teo is a cavalry unit attacking a naval base in the middle of a lake, the Navy should have been sent in instead and would have probably crushed the Liberation Army.
2)Suggesting to recruit Lepant
Honestly, this is something that can be argued about JRPGs in general to some extent. Still if you look at the fact Lepant is the head of a powerful merchant company, chances are he's a valuable source of money and resources for the army so getting him was quite important if that was the case. He's also famous, so getting him to join would probably add some widespread appeal to the Liberation Army's cause.
3)Orchestrated creating the forged document to save Liukan
Also not a bad plan, I mean they needed someone to help fight against a guy using biological weapons on people. Your forces can't even get close to the castle due to the pollen and god knows a clever use of a wind rune could probably knock out a long range siege trying to kill the plant with arrows, fire, or catapults. I mean Milich is a master swordsmen and magician.
4)Fooling the spy into thinking there was a training exercise while attacking the northern checkpoint
This is brilliant simply because the bad intel given simply tells the Scarlet Moon Empire superiors that the spy has been compromised and his intel can't be trusted anymore, notice how it's never brought up again until the spy reveals himself? Sanchez could have easily warned Kasim Hazel about Mathiu's plan to send diversionary forces to the border fortresses to get the main army out and allow the Liberation Army to sneak into his fortress but it doesn't seem that Kasim did do it, if the info was reported, or Sanchez didn't tell them because he wasn't sure the plan was the real plan... Seriously, this was one of the better plans he formed and one that is pretty common in real world battle situations.
5)Getting the city-states to ambush Kasim's forces.
As was stated, the Liberation Army didn't have the numbers to win a direct assault against him, the fact that what appears to be a rescue mission turns into a victory for the Liberation Army is pretty clever on Mathiu's part. This plan also, as has been stated already in this thread, reduced military casualties for the Liberation Army, and better yet, will keep the rather large chunk of Kasim's forces busy trying to hold off the City-States of Jowstone instead of coming from behind and attacking the Liberation army in a pincer attack when they try to take Gregminster. This was quite a clever plan and was also some pretty clever foreshadowing of the political conflicts seen in Suikoden II.
6)Making Ice boats to storm Sonya's fortress
There are two problems with the TC's alternate plan to take Shasarazade:
1) Anji's pirate crew would probably have been killed in the process of just trying to get Sonya's attention, it's pretty clear she has no tolerance for pirates. Not to mention this act would probably had resulted in her forces storming the Toran Lake Castle, which would have probably ended with a blockade and the Liberation Army would have been waited out in a long siege.
2) You don't even realize she has a grudge against Tir until you meet her at the storming of Shasarazade, so their would have not been any way for the Liberation Army to know that such a tactic was a possibility.
While I can concede that the Ice Boat strategy is silly and even with surprise on their side, there is no way the Liberation Army would have been able to get into the fortress without experiencing some heavy casualties cause let's face it, we have people in flimsy boats made of ice going up against the countries actual navy, it's like Sir Francis Drake going up against the Spanish Armada with a fleet of life boats and the element of surprise. It would have been ugly...
So overall, I don't consider Mathiu all that bad of a strategist, he just happens to appear in the game that had an inexperienced design team, so he comes off pretty underwhelming compared to later Strategists. It's the same reason why people give the plot some slack compared to SIV, I mean it's hard to justify judging an early work with the same criteria of the later work.