Bloodbowl Skaven - the short version
Ahh, I could wax lyrical about these guys for aaaages. Let’s try and limit the love though and say that the skaven team is the fastest in the game, with one of the genuine greats in the gutter runner. As you might expect, they’re fairly fragile.
Linemen. Fastest linemen in the game, but with AV7 they don’t like getting hit. Average agility means these guys are largely going to be sacrificial pawns until they’ve skilled up a bit. Stormvermin are the blitzers, tougher than the linemen and with block they’re a pretty standard blitzer, but limited to two in the team, which hurts a bit. The Thrower is basically your standard thrower with sure hands and pass. He’s only agility 3 though so until those skills start piling up you’ll need to use his speed to make the passes as short as possible. The Rat Ogre. Big, bad and crazy, he’s easily the strongest player on your team, but with the usual big guy issues (loner) added to frenzy you’ll need to be careful with him. He’s also not a line of scrimmage big guy – keep him back for picking on the weak and helpless. The gutter runner is the all-star of the team. These guys can do almost anything, with only their ST2 holding them back. Still, they can be decent sackers with strip ball and you can guarantee that if you’ve got one in your opponent’s half they’ll be wary of them scoring a lightning fast touchdown. Skaven need to make use of this speed to be their most successful, avoiding grinds and stealing the ball to race in for a touchdown and reset.
The skaven are an unusual team in that they’re fragile enough for a finesse play but not generally that agile. This benefits them in the long run as they can usually hurt the real finesse teams whilst still being fast enough to capitalise on mistakes. Keep the gutter runners in the game and you’ll always have a chance.
Bloodbowl Skaven - the longer version
The Skaven team is, without doubt, the fastest in the bloodbowl roster, all across the board. Gutter Runners have no equal in terms of outright pace, whilst even their big guy is quick enough to keep pace with an average lineman.
What this team isn't however, is an outright finesse team - most of the players are only average agility so you won't want to be trying too many fancy plays, long passes or dodges with them. If any team out there survives on its reliance on a single player type, it's the Skaven, where every other player's role is simply to make getting the ball to the gutter runners easier. Linemen get in the way of hits, Blitzers or the Rat Ogre clear a path in the wider zones, whilst the Thrower retrieves the ball and gets as close to the target of his pass as possible, then the throw is made, the Gutter Runner catches the ball and he's off, BOOOM! Touchdown, simple as.
One of the important things to remember with the skaven is that most of them are also lightly armoured, they do not cope well in a slug fest unless it's against the really weak teams. Keep a close eye on your number of knocked out players, as these can at least get back onto the pitch, if this part of the dugout is full, then keep the pressure on and try to force the pace as regular touchdowns will allow you to potentially bring these guys back into the game.
The Skaven also have to only reasonable access to that miraculous concept, the OTTD master (One Turn Touch Down).
Lightly armoured, with average agility, the only thing that really goes in the favour of these guys is their speed, since they are able to scramble a defence better than any other standard lineman. Sometimes all that is needed is to get players in the way of the opponent and force them to make some dice rolls, a task which the humble Skaven lineman is excellent at achieving.
Beyond that, don't expect anything of them, they are there to get hit instead of your more valuable players and put tackle zones on people to stop them moving freely around the pitch.
As for development in a league format, 'block' is the go-to skill for any lineman first, though potentially you could ignore this for an armour value increase, but that would probably be my only deviation for them. After that you probably want to develop a dirty player or two (getting other team's players off the pitch is a valid tactic for Skaven!), pick up Guard for anyone who rolls a double, and take any strength increases you might get with open arms.
A Thrower is, to my mind, an esential component of a successful Skaven team, and if you can develop a pair of them, even better! Don't forget though that he only has an average agility score, so throwing out long bombs in your first game aren't really advisable. Once his major role is accomplished however, he can also become a notable defensive asset to the team thanks to his likely positioning and speed. Position this guy in the central column of the pitch and he can reach either side in a single turn.
In league play, these guys really come into their own on one proviso - they absolutely need one of two things, either a double roll early on, or an increase in agility. They shouldn't be doing much dodging and sure hands should also help them be quite reliable at actually picking the ball up, but being able to pass further, more consistently allows the Thrower to pick and choose the targets of their passes, and it becomes viable to infiltrate several Gutter Runners into the opposing territory before choosing your pass.
In that respect therefore, take an agility increase as soon as you get it, and on a double choose 'Strong Arm'. 'Hail Mary Pass' wouldn't hurt either, since you can actually build up a lot of distance between them and their Gutter Runner team mates if you're not careful. All the usual throwing skills apply though, 'Accurate' for a generic boost, 'Safe Throw' is great for popping the ball over a crowd, and 'Nerves of Steel' is a godsend if your Thrower gets scragged. I also quite like to deveop a Thrower with 'kick' and another with 'kick-off return' to be able to more easily pin an opponent back into their half, and to grab possession easier in return.
As I said above, the star of the team, two not uncommon increases will turn your average Gutter Runner into a maestro of the bloodbowl art, the One-Tun Touchdown specialist. The first of those is an increase in Movement. Take this the moment you see it as it gives the player a basic movement of 10 squares (it takes 13 to cross from the line of scrimmage to the end zone). Your next skill is 'Sprint', and then you have a player who can make those 13 squares seem easy. After that, I'd take 'Sure Feet' to limit the damage of any sprinting failures, then see what takes your fancy.
Equally, the Gutter Runner can be a highly effective Catcher if you've properly developed a Thrower along the lines indicated above. 'Catch' and 'Diving Catch' combine beautifully with their innate high agility, and then you take 'Nerves of Steel' on a doubles roll.
The Gutter Runner also presents an alternative to those players who find the Thrower's agility to be an issue. Being able to take up to 4 of these guys means that it's not a great leap to leave out the Thrower, and take a Gutter Runner instead. Sure, he doesn't have access to 'sure hands' or 'pass', but his natural agility means that's less of an issue anyway. It's certainly not imprudent to use the Gutter Runner in a throwing role until such time as your Thrower develops sufficiently to get his own game in a more reliable state.
The classic Blitzer positional player quite frankly, slightly more heavily armoured than his team mates, and comes with the block skill from the start. If the team could take more than two of these guys then the Skaven would be a team of epic proportions. As it is, his armour isn't significantly high enough to keep him reliably safe, and with only two in the team any loss will be keenly felt. That being said though, they're your most reliable offensive players when it comes to making space for your Gutter Runners.
I tend to avoid splitting these guys up on the field of play if at all possible, they attain a much greater level of threat when paired together, and as with all skaven, they are quick enough to cross the field to counter any other threats there might be on the opposite flank.
I tend however to skill these guys up in two very different ways if possible during league play. The first becomes a guard using his access to the strength skills, bolstering the Skaven line around him with skills like 'Guard', and 'Stand Firm', whilst the second becomes my dedicated basher. Unless you get a strength increase (which you take) he then takes things like 'Frenzy', 'Pile On', and 'Mighty Blow'. The other real bonus that the Skaven get is access to the Mutations, and of these, 'Claw' is worth its weight in gold against the teams you normally struggle against, those with high armour values.
Finally we have the Rat Ogre, a nasty growling ball of fur and rage if ever I saw one, his negative big guy trait is one of the less annoying ones, because he'll rarely fail his test if you're hitting something with him, which is what you want to be doing anyway.
As I alluded to earlier, tactically the Rat Ogre isn't really designed to be on the line of scrimmage, sure he's strong and with 'mighty blow' he's just as capable as any other big guy of dealing damage, but no other big guy wears less armour and his prehensile tail is extremely useful for helping to guard your flanks from annoying agile catchers and runners making their way round your defence. It also means he's particularly good for picking on weaker players out on the flanks, with frenzy often allowing him to push opponents into the crowd.
In terms of league play and developing skills, as ever if you roll a double then take 'block', otherwise juggernaut can be a good substitute, particularly so in the case of the Rat Ogre as being out on the flanks means you can be more likely to blitz than on the Line of Scrimmage.
More than almost any other big guy, the Rat Ogre is a bully, he's strong and relatively tough for a skaven but you can't be risky with him, as you'll pay the price if he gets ganged up on. Keep him on the flanks and use him to prey on the weak, and you'll get the most out of this beast.
Without a doubt, Skaven are one of the stronger blood bowl teams available, but they have to be played correctly to be so, play them wrong and you end up with a good number of your team in the injured box, and the opponent carrying the ball.
Stick to the basics, take the hits on your linemen, use your blitzers to make space and unleash the Gutter Runners into it and you'll do fine.